Answer:
1470Joules
Explanation:
Workdone = Force * distance
Since the worker pushes the crate up the 3m ramp. The distance covered is 3m
Force = Mass * Acceleration due to gravity
Force = 50*9.8
Force = 490N
Workdone = 490 * 3
Workdone = 1470Joules
Hence I did 1470Joules of work
in a hydraulic garage the small piston has a radius of 5 cm and the large piston has radius of 15 cm what force must be applied to the small piston in order to lift a car weighting 20000 N on the large piston
The force applied to small piston = 2.2 x 10³ N
Further explanationGiven
a radius of 5 cm and 15 cm
weight 20000 N
Required
Force applied
Solution
Pascal Law :
F₁/A₁=F₂/A₂
A₁ = π.5²
A₂ = π.15²
F₁/ π.5² cm² = 20000/π.15² cm²
F₁ = 2222.22 N⇒2.2 x 10³ N
Billy is trying to shine a laser off a mirror at the end of a basketball court into Sam's eyes to distract him (Billy is evil). Sam is at a 38 degree reflection angle from the mirror. At what angle does Billy need to shine the laser at the mirror to get it in Sam's eyes.
Answer:
When we have a plane interface, the angle of incidence of the ray is the same as the angle of reflection.
In this case, we have a mirror (we assume that it is plane) and we know that we need to have an angle of reflection equal to 38° in order to reach Sam.
Then the angle of incidence of the ray must also be exactly 38°.
Then Billy needs to shine his laser at an angle of 38° at the mirror.
(where the angle is measured between the normal line to the surface of the mirror and the incident ray)
Billy needs to shine the laser at an incident angle of 38 degrees.
LASER is an acronym that stands for “light amplification by the stimulated emission of radiation.” We know that according to the laws of reflection, the angle of incidence is equal to the angle of reflection.
As such, knowing that Sam is at a 38 degree reflection angle from the mirror, Billy needs to shine the laser at an incident angle of 38 degrees.
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You need to focus a 10 mW, 632.8 nm Gaussian laser beam that is 5.0 mm in diameter into a sample. You have access to a lens with a focal length of 6.0 cm and focal length of 12.0 cm. For both lenses, the light fills the size of the lens. Using the Gaussian beam equations, what is the smallest diameter of the beam (known as the beam waist) for each lens
Answer:
ee that the lens with the shortest focal length has a smaller object
Explanation:
For this exercise we use the constructor equation or Gaussian equation
[tex]\frac{1}{f} = \frac{1}{p} + \frac{1}{q}[/tex]
where f is the focal length, p and q are the distance to the object and the image respectively.
Magnification a lens system is
m = [tex]\frac{h'}{h}[/tex] = - [tex]\frac{q}{p}[/tex]
h ’= -\frac{h q}{p}
In the exercise give the value of the height of the object h = 0.50cm and the position of the object p =∞
Let's calculate the distance to the image for each lens
f = 6.0 cm
[tex]\frac{1}{q} = \frac{1}{f } - \frac{1}{p}[/tex]
as they indicate that the light fills the entire lens, this indicates that the object is at infinity, remember that the light of the laser rays is almost parallel, therefore p = inf
q = f = 6.0 cm
for the lens of f = 12.0 cm q = 12.0 cn
to find the size of the image we use
h ’= h q / p
where p has a high value and is the same for all systems
h ’= h / p q
Thus
f = 6 cm h ’= fo 6 cm
f = 12 cm h ’= fo 12 cm
therefore we see that the lens with the shortest focal length has a smaller object
The bat emits a sound wave with a frequency of 25.0 kHz and a wavelength of 0.0136
metres.
Calculate the speed of this sound wave.
Answer:
The calculation that you then need to do is 25000 x 0.0136 = 340. You must not forget the units of speed, which here are metres per second, or m/s. Your final answer is 340 m/s.
Definiti: a)Marimile Fizice Vectoriale
b)Fortele Concurente
No lo se hsjdhdhfhjdhshdhdhhd
An electron has a mass of 9.1x10-31 kg. What is its momentum if it is travelling at a speed of 3.5x106 m/s?
Answer:
3.19*10^-24
Explanation:
the equation to find momentum is p=mv so you just multiply the mass times velocity
An electron has a mass of 9.1x10⁻³¹ kilograms. if it is traveling at a speed of 3.5x10⁶ meters/seconds then its momentum would be 3.185 ×10⁻²⁴ kgm/s.
What is momentum?It can be defined as the product of the mass and the speed of the particle, it represents the combined effect of mass and the speed of any particle, and the momentum of any particle is expressed in Kg m/s unit.
As given in the problem an electron has a mass of 9.1x10⁻³¹ kilograms. if it is traveling at a speed of 3.5x10⁶ meters/seconds then its momentum would be
the momentum of the electrons = mass of the electron×velocity of the electron
= 9.1x10⁻³¹ × 3.5x10⁶
= 3.185 ×10⁻²⁴ kgm/s
Thus, the momentum of the electron would be 3.185 ×10⁻²⁴ kgm/s.
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Francine is dragging a heavy toolbox across a rough, cement floor.
What is a contact force that is acting on the box as Francine pulls it.
A.
static electricity
B.
gravity
C.
magnetism
D.
friction
Answer:
D. Friction
Explanation:
Answer:
d. friction
I took it on study island and got it correct thanks to the other guy that has answered
Explanation:
calculate the peak voltage of a mains supply of 240Vrms.
Two cellists, one seated directly behind the other in an orchestra, play the same note for the conductor who is directly in front of them. Because of the separation between the cellists, destructive interference occurs at the conductor. This separation is the smallest that produces destructive interference. Would this separation increase, decrease, or remain the same if the cellists produced a note with a higher frequency
Answer:
Please see below as the answer is self-explanatory.
Explanation:
In order to have a destructive interference, the path difference between the sources of the sound, must be equal to an odd multiple of the semi-wavelength, as follows: ⇒ d = d₂ - d₁ = n*(λ/2) The minimum posible value for this distance, is when n=1, as it can be seen here: dmin = λ/2 In any traveling wave, there exists a fixed relationship between the wave speed, the frequency and the wavelength: v = λ*f Therefore, assuming that the speed of sound keeps constant, if the frequency is increased, in order to keep the right side of the expression above balanced, λ must be decreased.As the smallest separation that produces destructive interference is directly proportional to the wavelength, this means that this separation will decrease if the cellists produced a note with a higher frequency.I’m not sure how to solve this
Answer:
Option 10. 169.118 J/KgºC
Explanation:
From the question given above, the following data were obtained:
Change in temperature (ΔT) = 20 °C
Heat (Q) absorbed = 1.61 KJ
Mass of metal bar = 476 g
Specific heat capacity (C) of metal bar =?
Next, we shall convert 1.61 KJ to joule (J). This can be obtained as follow:
1 kJ = 1000 J
Therefore,
1.61 KJ = 1.61 KJ × 1000 J / 1 kJ
1.61 KJ = 1610 J
Next, we shall convert 476 g to Kg. This can be obtained as follow:
1000 g = 1 Kg
Therefore,
476 g = 476 g × 1 Kg / 1000 g
476 g = 0.476 Kg
Finally, we shall determine the specific heat capacity of the metal bar. This can be obtained as follow:
Change in temperature (ΔT) = 20 °C
Heat (Q) absorbed = 1610 J
Mass of metal bar = 0.476 Kg
Specific heat capacity (C) of metal bar =?
Q = MCΔT
1610 = 0.476 × C × 20
1610 = 9.52 × C
Divide both side by 9.52
C = 1610 / 9.52
C = 169.118 J/KgºC
Thus, the specific heat capacity of the metal bar is 169.118 J/KgºC
I need helpp! This is urgent tomorrow is the duedate
Answer:
The Force that resists the motion of one object moving relative to another is Friction. Kinetic Friction Resists the motion of Moving objects, while Static friction keeps the objects from moving.
You have been handed an unknown battery. Using your multimeter, you determine that when a 4.30 resistor is connected across the battery's terminals, the current in the battery is 0.500 A. When this resistor is replaced by an 9.4 resistor, the current drops to 0.250 A. From those data, find the emf and internal resistance of your battery.
Answer:
Ri = 0.8 Ω
V= 2.55 V
Explanation:
Since the internal resistance of the battery is connected in series with the resistor connected across the battery's terminals, applying Ohm's Law, we can write the following equation, when R₁=4.30 Ω, and I₁=0.500A:[tex]I_{1} = \frac{V}{R_{i} + 4.3 \Omega } = 0.500 A (1)[/tex]
We can apply exactly this same expression, when R₂ = 9.4Ω, and I₂ = 0.250A:[tex]I_{2} = \frac{V}{R_{i} + 9.4 \Omega} } = 0.250 A (2)[/tex]
Now, we can divide (1) by (2) as follows:[tex]\frac{R_{i} + 9.4 \Omega}{R_{i} + 4.3 \Omega} = \frac{I_{1} }{I_{2}} = 2 (3)[/tex]
Solving for Ri, we get Ri = 0.8 ΩReplacing this value in (1) we can solve for V, as follows:V = I₁ * (Ri + R₁) = 0.500 A * (0.8Ω + 4.3Ω) = 2.55 V⇒ V = 2.55 V (emf of the battery)
What is the physiological response of the body when exercise is stopped instantaneously?
Blood flow rapidly decreases and blood pools in your feet
Blood flow rapidly decreases and lung capacity increases
Blood flow rapidly increases and heart rate decreases
Blood flow rapidly increases and blood pools in your hands
Answer:
Blood flow rapidly decreases and blood pools in your feet
Explanation:
Because I did the test and if u don't want to except my answer then ***** but if u do and get it right mark it the best. OK?
Answer:
The answer is A blood flows rapidly decreases blood pools in your feet
Explanation:
I hope the helps i just did the quiz/test and got it correct
1. A flagpole consists of a flexible, 5.99 m tall fiberglass pole planted in concrete. The bottom end of the flagpole is fixed in position, but the top end of the flagpole is free to move. What is the lowest frequency standing wave that can be formed on the flagpole if the wave propagation speed in the fiberglass is 2730 m/s?
2. Suppose that a standing wave on the flagpole gives rise to a sound wave of the same frequency. A person would be able to hear the sound produced by the above standing wave, since the average human being can detect sounds at frequencies between 20.0 Hz and 20.0 kHz. A nearby mouse, however, can only detect frequencies between 1.01 kHz and 90.0 kHz. What is the lowest flagpole harmonic that the mouse can hear?
a. 2nd.
b. 10th.
c. 6th.
d. 11th.
Answer:
Explanation:
The flagpole will act as closed organ pipe . If λ be wavelength of wave produced ,
n x λ / 4 = L where L is length of pole . n is odd integer like 1 , 3 , 5 ,7 etc .
λ = 4 L / n
for lowest frequency , wavelength will be highest . For highest λ , n = 1
λ = 4 L = 4 x 5.99
= 23.96 m
frequency of wave = speed of wave / wavelength
= 2730 / 23.96 = 114 approx .
2 )
The frequency range heard by mouse = 1010 Hz to 90000 Hz .
The fundamental frequency ( lowest harmonic ) of flagpole is 114 Hz
Higher odd harmonics are also possible . If n be the lowest harmonic in the audible range of mouse ,
n x 114 = 1010
n = 8.85 or 9 th or 11 th
9 th is not in the option , 11 th is the right option .
d . 11 th is the answer .
1. The lowest frequency standing wave that can be formed on the flagpole is 114 Hz.
2. The lowest flagpole harmonic that the mouse can hear is 11th. Hence, option (d) is correct.
What is the frequency of the sound wave?When a sound wave is propagating through any medium, such that the total wave produced in one second, is known as the frequency of the sound wave.
1.
Given data:
The height of fiberglass is, h = 5.99 m.
The wave propagation speed in fiberglass is, v = 2730 m/s.
The flagpole will act as a closed organ pipe. If λ be the wavelength of the wave produced,
n x λ / 4 = L
here,
L is the length of the pole.
n is an odd integer like 1, 3, 5,7, etc.
Arranging the above expression as,
λ = 4 L / n
for the lowest frequency, the wavelength will be the highest . For highest λ , n = 1
λ = 4 L
λ = 4 x 5.99
λ = 23.96 m
frequency of wave = speed of wave / wavelength
frequency of wave = 2730 / 23.96
frequency of wave = 114 Hz
Thus, we can conclude that the lowest frequency standing wave that can be formed on the flagpole is 114 Hz.
2.
The frequency range heard by the mouse = 1010 Hz to 90000 Hz.
The fundamental frequency ( lowest harmonic ) of the flagpole is 114 Hz.
Higher odd harmonics are also possible. If n be the lowest harmonic in the audible range of mouse,
n x 114 = 1010
n = 8.85 or 9 th or 11 th
Thus, we can conclude that the lowest flagpole harmonic that the mouse can hear is 11th. Hence, option (d) is correct.
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Running along a rectangular track 50m × 40 m you complete one lap in 100 s. What is your average velocity for the lap ?
Answer:
1.8 m/s
Explanation:
Distance = 2*50 +2*40 [m] = 180 [m]
Time = 100 [s]
Velocity = Distance/Time = 1.8 m/s
Average velocity for the lap is 1.8 m/s
GIven:
Length of rectangular track = 50 m
Width of rectangular track = 40 m
Time taken to cover a lap = 100 seconds
Find:
Average velocity for the lap
Computation:
Perimeter of rectangle = Length of one lap
So,
Perimeter of rectangle = 2(l + b)
So,
Length of one lap = 2[50 + 40]
Length of one lap = 2[90]
Length of one lap = 180 meter
Average velocity = Distance / Time
Average velocity for the lap = 180 / 100
Average velocity for the lap = 1.8 m/s
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Are you better off in an accident where the hood is
deformed or where the car is not damaged at all but
bounces backward?
Answer:
you would be better off if the car bounced backwards
Explanation:
because if the hood was dismembered than you have a high chance of very bad injury but if it is just bounced back you would have less chance of getting hurt if properly sitting and seat belted.
Calculate P3 (in W). W (b) Find the total power (in W) supplied by the source. W Compare the total power with the sum of the powers dissipated by the resistors. (Consider two values to be equal if they are within 3% of each other.) The total power is less than the sum of the powers dissipated by the resistors. The total power is equal to the sum of the powers dissipated by the resistors. The total power is greater than the sum of the powers dissipated by the resistors.
Answer:
the principle of conservation of energy cannot be violated.
the correct one is: The total power is equal to the sum of the powers dissipated by the resistors.
Explanation:
The power in an electric circuit is given by
P == I V
In a circuit with several components (resistors) the power dissipated is the current by the voltage in each resistance, by the principle of conservation of energy the current in each resistance is the same if the circuit is in series and the current is the same if The circuit is in parallel, but cannot be greater than the current supplied by the power source.
Therefore, the power dissipated by the entire circuit is the sum of the power dissipated by each part, since the principle of conservation of energy cannot be violated.
When reviewing the answers, the correct one is: The total power is equal to the sum of the powers dissipated by the resistors.
To understand the cause of constructive and destructive interference for the double-slit experiment, and to explain how the interference pattern depends on the parameters of the emitted waves.For this tutorial, use the PhET simulation Wave Interference. This simulation allows you to send waves through a variety of barriers and look at the resulting interference patterns.Start the simulation. You will see three possible selections: Waves, Interference, and Slits. To change between simulations at any point, select the desired simulation on the toolbar located at the bottom of the screen. In these simulations you can choose between water waves, sound waves, or light. You can adjust the slit width and slit separation using slider bars, and you can put a barrier containing one or two slits in front of the source of the waves. There are also several measuring tools at the upper-right hand corner of the screen, including a detector that produces plots showing the wave amplitude vs. time for the location of the two sensors on the detector, which can be dragged to any location.Feel free to experiment with all of the simulations to get a feel for how they work. When you are done, and before starting Part A, set the simulation to Waves, and select the Reset icon.Select Light for the type of wave, adjust the wavelength so that the light is red, and increase the amplitude of the light to the max. Then, select the start button at the source location to begin producing the waves.Light is a form of electromagnetic wave, containing oscillating electric and magnetic fields. The wave amplitude detector mentioned above shows how the electric field oscillates in time at the location of the probe. The amplitude of the wave at the location of the probe is equal to the maximum electric field measured.How does the amplitude of the wave depend on the distance from the source?a. The amplitude decreases with distance.b. The amplitude increases with distance.c. The amplitude is constant.
Answer:
The maximum intensity, if it changes with distance, the correct answer is a
Explanation:
After reading your extensive writing on the phenomenon of interference, I see that your question is not very related to it
In the interference experiments the amplitude of the radiation is given by the sum of the intensity of a point of the two waves coming from the slits,
I =[tex]I_{max }[/tex] cos² ([tex]\frac{\pi \ d \ sin \theta}{\lambda}[/tex]) sinx / x
x = [tex]\frac{\pi \ a \ sin \theta }{ \lambda }[/tex]
where d is the separation between the slits and a the width of each slit.
Therefore, we can see that the intensity of the radiation is redistributed in space in lines approximately the same intensity, second factor is due to the diffraction of each slit, this is generally small for the central part of the interference pattern
therefore the interference pattern is made up of lines of equal intensity.
The maximum intensity, if it changes with distance, in general for energy conservation the intensity must decrease with distance, therefore the correct answer is a
I need the named chemical compounds
Answer:
1 Acetaldehyde C2H4O
2 Acetamide C2H5NO
3 Acetic acid CH3COOH
4 Acetone C3H6O
Explanation: These are the only ones I know
An Olympic high jumper, with a mass of 82 kg, has a
maximum gravitational potential energy of 1970 J. How
high was the jump?
Answer:
I don't really know
Explanation:
I really wanted to help you, but then I realized i didnt know how to
The particle in the atom with a negative charge is the ______
Answer here
Answer:
Explanation:
The electron has a negative charge. Proton is positive and neutron is neutral.
What is the motion and arrangement of molecules in a liquid
Answer:
particles
Explanation:
in liquids, particle are close together
A 1800 kg hybrid vehicle operates on ethanol and is equipped with a multipurpose motorgenerator-flywheel. When the vehicle slows or stops, 50% of the kinetic energy is recovered as electrical energy in the battery. When the IC engine is used to recharge the battery, there is a 25% efficiency of converting chemical energy in the fuel to electrical energy stored in the battery. The vehicle slows from 70 miles per hour to 20 miles per hour. Calculate:
This question is incomplete, the complete question is;
A 1800 kg hybrid vehicle operates on ethanol and is equipped with a multipurpose motorgenerator-flywheel. When the vehicle slows or stops, 50% of the kinetic energy is recovered as electrical energy in the battery. When the IC engine is used to recharge the battery, there is a 25% efficiency of converting chemical energy in the fuel to electrical energy stored in the battery. The vehicle slows from 70 miles per hour to 20 miles per hour. Calculate: (A) Electrical energy recovered in the battery in [kJ] (B) Mass of fuel needed to store same amount of energy in the battery in [kg]
Answer:
a) Electrical energy recovered in the battery is 404.6895 kJ
b) Mass of fuel needed to store same amount of energy in the battery is 0.0606 kg
Explanation:
Given that;
Initial speed of the vehicle V = 70 miles per hour = 31.293 m/s
Final speed of the vehicle u = 20 miles per hour = 8.941 m/s
mass of vehicle m = 1800 kg
Noe, change in kinetic energy of the vehicle will be;
[tex]E_{kinetic}[/tex] = [tex]\frac{1}{2}[/tex]m( v² - u² )
we substitute
= [tex]\frac{1}{2}[/tex] × 1800( (31.293)² - (8.941)² )
= 900( 979.2518 - 79.9414)
= 900 × 899.3104
= 809379.36 J
[tex]E_{kinetic}[/tex] = 809.379 kJ
now, Electrical energy recovered in the battery when the vehicle slows will be;
[tex]E_{battery}[/tex] = 50% × [tex]E_{kinetic}[/tex]
[tex]E_{battery}[/tex] = 50/100 × 809.379 kJ
[tex]E_{battery}[/tex] = 404.6895 kJ
Therefore, Electrical energy recovered in the battery is 404.6895 kJ
b)
For this electrical energy to be obtained from fuel, the chemical energy required will be;
[tex]E_{chemical}[/tex] = [tex]E_{battery}[/tex] / 25%
[tex]E_{chemical}[/tex] = 404.6895 kJ / 0.25
[tex]E_{chemical}[/tex] = 1618.758 kJ
Heat energy released per mass of ethanol combustion
(Lower heating value of ethanol) is 26.7kJ/g
Now, the mass of fuel needed to generate 1618.758 kJ will be;
[tex]m_{fuel}[/tex] = 1618.758 kJ / 26.7kJ/g
[tex]m_{fuel}[/tex] = 60.63 g
[tex]m_{fuel}[/tex] = 0.0606 kg
Therefore, Mass of fuel needed to store same amount of energy in the battery is 0.0606 kg
How does the length of the pendulum affect the amount of potential energy it starts with? (A longer string will have a greater change in height for the same angle)
Answer:
This is somewhat of a confusing question.
Zero potential energy is usually used to refers to the zero potential energy of objects at infinity. Thus, bringing an object from infinity requires negative work because work is done by the object. One could also choose the pivot point of the pendulum as zero potential. Then any objects above the pivot point would be at a positive potential, and objects below the pivot point would have a negative potential (the object does work moving to a point of lower potential).
Basically, work done "on" an object requires positive potential energy input while work done "by" the object requires negative energy input.
Those are the basic considerations in solving potential energy problems.
g You are walking around your neighborhood and you see a child on top of a roof of a building kick a soccer ball. The soccer ball is kicked at 37° from the edge of the building with an initial velocity of 21 m/s and lands 63 meters away from the wall. How tall, in meters, is the building that the child is standing on?
Answer:
h = 21.5 m
Explanation:
First of all, we define a pair of coordinate axes along the horizontal and vertical direction, calling x-axis to the horizontal and y-axis to the vertical, with the origin in the point where the ball is kicked.Neglecting air resistance, the only influence on the ball once kicked is due to gravity, so the ball is accelerated by the Earth with a constant value of -9.8 m/s2 (assuming the upward direction as positive).So, we can use the kinematic equation for displacement for the vertical direction, as follows:[tex]\Delta y = v_{oy}* t -\frac{1}{2}*g*t^{2} (1)[/tex]
Since the ball is kicked at an angle of 37º from the edge of the building, at an initial velocity of 21 m/s, we can find the horizontal and vertical initial speeds as follows:[tex]v_{ox} = v* cos 37 = 21 m/s * cos 37 = 16.8 m/s (2)[/tex]
[tex]v_{oy} = v* sin 37 = 21 m/s * sin 37 = 12.6 m/s (3)[/tex]
In the horizontal direction, since gravity has no component in this direction, the ball moves at a constant speed, equal to v₀ₓ.Applying the definition of average velocity, since we know the horizontal distance traveled, we can find the total time that the ball was in the air, as follows:[tex]t = \frac{\Delta x}{v_{ox} } = \frac{63m}{16.8m/s} = 3.75 s (4)[/tex]
Replacing (4) and (3) in (1), we can find the total vertical displacement, which is equal to the height of the building, as follows:[tex]-h = 12.6m/s* 3.75s -\frac{1}{2}*(9.8m/s2)*(3.75s)^{2} = -21.5 m (5)[/tex]
⇒ h = -(-21.5m) = 21.5 mA museum curator pulls a 150 kg sculpture across the museum floor, with an acceleration of 0.5 m/s2. Calculate the force with which the curator pushes the sculpture in Newtons.
Answer:
F = 75 N
Explanation:
Given that,
Mass of a sculpture, m = 150 kg
The acceleration of the sculpture, a = 0.5 m/s²
We need to find the force with which the curator pushes the sculpture.
F = ma
Substitute all the values of m and a in it.
F = 150 kg × 0.5 m/s²
= 75 N
So, the required force with which the curator pushes the sculpture is 75 N.
From the center of the Earth to the moon, what should the orbital radius of such satellite be in order to stay over the same point on the earth’s surface?
In order to have a period that matches the Earth's rotation, a satellite must be in a circular orbit, and 42,164 km from the center of the Earth.
But that's not quite enough to make sure that it always stays over the same point on the Earth's surface (and appears motionless in the sky). For that to happen, the satellite's orbit has to be directly over the Equator.
The Moon has nothing to do with any of this.
The x vector component of a displacement vector has a magnitude of 146 m and points along the negative x axis. The y vector component has a magnitude of 113 m and points along the negative y axis. Find (a) the magnitude and (b) direction of . Specify the direction as a positive angle with respect to the negative x axis.
Answer:
a) the magnitude of r is 184.62
b) the direction is 37.74° south of the negative x-axis
Explanation:
Given the data in the question;
as illustrated in the image blow;
To find the the magnitude of r, we will use the Pythagoras theorem
r² = y² + x²
r = √( y² + x²)
we substitute
r = √((-113)² + (-146)²)
r = √(12769 + 21316 )
r = √(34085 )
r = 184.62
Therefore, the magnitude of r is 184.62
To find its direction, we need to find ∅
from SOH CAH TOA
tan = opposite / adjacent
tan∅ = -113 / -146
tan∅ = 0.77397
∅ = tan⁻¹( 0.77397 )
∅ = 37.74°
Therefore, the direction is 37.74° south of the negative x-axis
A 72-kg man stands on a spring scale in an elevator. Starting from rest, the elevator ascends, attaining its maximum speed of 1.2 m/s in 0.80 s. The elevator travels with this constant speed for 5.0 s, undergoes a uniform negative acceleration for 1.5 s, and then comes to rest. What does the spring scale register During the first 0.80s of the elevator’s ascent?
Answer:
Explanation:
During the first .8 s , the elevator is under acceleration . It starts from initial velocity u = 0 , final velocity v = 1.2 m /s , time = .8 s
v = u + at
1.2 = 0 + .8 a
a = 1.2 / .8
= 1.5 m /s²
During the acceleration in upward direction , let reaction force of ground on man be R .
Net force on man = R - mg
Applying Newton's 2 nd law
R - mg = ma
R = m ( g + a )
= 72 ( 9.8 + 1.5 )
= 813.6 N .
This reaction force will be measured by spring scale , so reading of spring scale will be 813.6 N .
For each of the motions described below, determine the algebraic sign (+, -, or 0) of the velocity and acceleration of the object at the time specified. For all of the motions, the positive y axis is upward.Part A. An elevator is moving downward when someone presses the emergency stop button. The elevator comes to rest a short time later. Give the signs for the velocity and the acceleration of the elevator after the button has been pressed but before the elevator has stopped.Part B. A child throws a baseball directly upward. What are the signs of the velocity and acceleration of the ball immediately after the ball leaves the child's hand?Part C. A child throws a baseball directly upward. What are the signs of the velocity and acceleration of the ball at the very top of the ball's motion (i.e., the point of maximum height)?
Answer:
A. Velocity is negative (-)
Acceleration is positive,(+)
B. Velocity is positive. (+)
Acceleration is negative (-)
C. Velocity is zero (0).
Acceleration is negative (-)
Explanation:
The elevator is said to be moving downward, therefore, its motion is in the negative direction as the positive direction is upward in the y-axis. Velocity is negative (-)
As the elevator is making an emergency stop, it is decelerating. Deceleration is negative acceleration. However, since it occurs in the opposite direction, i.e. acceleration vector is pointing upward, acceleration is positive,(+)
The motion of the ball is in the upward direction, therefore the velocity is positive. (+)
The acceleration due to the force of gravity acts in the opposite direction to that of the ball, i.e. downwards, acceleration is negative (-)
At maximum height, the ball will stop moving, therefore, velocity is zero (0).
Since acceleration due to the force of gravity acts downward, the acceleration is negative (-)