Answer:
Explanation:
For a person suffering from nearsightedness, far point is 3.5 m . That means , an object beyond 3.5 m will not be clearly visible by the person . Ray of light coming from 3.5 m will be focussed on retina . For an object to be visible from infinity , ray of light coming from infinity should appear to be coming from 3.5 m . In other words , the object placed at infinity should form a virtual image at 3.5 m . This can be done by concave lens.
u = ∝ ; v = 3.5
Using lens formula
[tex]\frac{1}{v} -\frac{1}{u} = \frac{1}{f}[/tex]
[tex]\frac{1}{-3.5} -0 = \frac{1}{f}[/tex]
f = - 3.5 m .
Explain why you cannot charge one end of a steel rod and
leave the other end uncharged.
Answer:
Because a steel rod is a good conductor which would make the charges produced to cascade easily from one end of the metal to another.
Explanation:
Charges are formed whenever an object gains or losses an electron. This can be easily produced by three major methods; friction, contact and induction.
Conductors, e.g metals (steel), are materials that would allow charges, electric current, or heat to flow through them easily. They have low resistance.
When a steel rod is charged at one end, the charges cascades from that end towards the other end because of the conducting property of the metal. Thereby it is very difficult to charge one end of the steel rod, while the other remains uncharged.
How did astronomers precisely determine the length of an Astronomical Unit in the 1960s?
Answer:
Use of telemetry and radar astronomy
Explanation:
An astronomical Unit (AU) is a unit of measuring distances in outer space, which is based on the approximate distance between the earth and the Sun.
After several years of trying to approximate the distance between the Sun and the Earth using several methods based on geometry and some other calculations, advancements in technology made available the presence of special motoring equipment, which can be placed in outer space to remotely monitor and measure the position of the sun.
The use of direct radar measurements to the sun (radar astronomy) have also made the determination of the AU more accurate.
A standard radar pulse of known speed is sent to the Sun, and the time with which it takes to return is measured, once this is recorded, the distance between the Earth and the Sun can be calculated using
distance = speed X time.
However, most of these means have to be corrected for parallax errors
Josh calculated that the speed of his balloon travelling a distance of 10m was 2m/s. What was the length of time?
what unit is used to measure the downwards force of weight?
Answer: Newton denoted using N
Examples: 25 N
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what did the biologist wear on his first date ?
Answer:
Calvin Cycles
Explanation:
This is a popular joke. Is this an answer choice for your question?
A soccer ball player bounces the ball off her head, changing the velocity of the ball. She changes the x-component of the velocity of the ball from vix = 7.9 m/s to vfx = 5.9 m/s and the y-component from viy = −3.4 m/s to vfy = 4.5 m/s.
If the ball has a mass of 0.40 kg and is in contact with the player's head for 7.1 ms, determine the direction of the impulse (in degrees counterclockwise from the +x-axis) delivered to the ball.
Answer:
Explanation:
change in momentum along x axis = mass ( final velocity - initial velocity )
= .4 ( 5.9 - 7.9 )
= - .8 kg m /s
change in momentum along y axis = mass ( final velocity - initial velocity )
= .4 ( 4.5 + 3.4 )
= 3.16 kg m/s
Force along x axis be Fx
Fx . t = change in momentum along x axis = - .8
Fy . t = change in momentum along y axis = 3.16
Direction of impulse =
Tanθ = Fy . t / Fx . t , θ is angle from x axis along anticlockwise direction.
= 3.16 / - 0 .8 .
= - 3.95
θ = 165.8 degree from positive x - axis. anticlockwise.
A motorcycle has a speed of 30 m / s. After braking, it decelerates with constant deceleration A = -3.0 m / s ^ 2
Calculates its speed after 3.0 s
[tex]a = \displaystyle\frac{v-u}{t}[/tex]
[tex]-3 = \displaystyle\frac{v - 30}{3}[/tex]
[tex]v -30 = -9[/tex]
[tex] v = 21 m/s[/tex]
Answer:21
Explanation:
Where is the density of the material greater, at point B or point C?
Explain why.
Answer: The density is greater at point C
Explanation: At that point
The convention current slowly cools off
Which landscape will erode more quickly? Assume the same precipitation and average temperature in each landscape.
A. Landscape A.
B. Landscape B.
C. The rates of erosion will be the same.
D. Impossible to determine.
Answer:
B. Landscape B
Explanation:
Shale is fine sediment pressed together to form rock.
Sandstone is larger (sand-grain-sized) sediment cemented together to form rock.
Shale erodes faster, as evidenced by the second attachment. That attachment shows erosion of a rock face consisting of interbedded shale and sandstone. The shale has receded significantly, leaving the sandstone layers with space between them.
21. If € = 8.0 V, at what rate is the emf providing energy to the circuit shown?
15 2
10 22
12 V
+
1022.
a. 8.4 W
b. 7.6 W
C.5.6 W
d. 11 W
e. 2.0 W
Answer:
c. 5.6 W
Explanation:
We can write the Kirchoff's voltage law (KVL) equations for the circuit using i1 for the clockwise current in the left loop, and i2 for the clockwise current in the right loop. Then the circuit equations are ...
i1 (10 +10) -i2(10) = 12
-i1(10) +i2(10 +15) = 8
Using Cramer's rule to find i2, we have ...
i2 = (12(-10) -8(20))/((-10)(-10) -(25)(20)) = -280/-400 = 0.7
The power supplied by the Emf is ...
(8 V)(0.7 A) = 5.6 W . . . . . matches choice C
Two astronauts of equal mass are holding on to each other and moving at a speed of 30 m/s. They push off of each other and one of the astronauts moves in the same direction as the two were initially moving but at 60 m/s. The velocity of the second astronaut is
Answer:
Zero
Explanation:
A periodic wave travels from one medium to another. Which pair of variables are likely to change in the process? A. velocity and wavelength B. velocity and frequency C. frequency and wavelength D. frequency and phase E. wavelength and phase
Answer:
A. velocity and wavelength
Explanation:
When a wave travels from one medium to another it undergoes refraction which results to the change in direction.
Refraction of a wave is one of the property of waves that occurs when a wave changes direction when it passes from one medium to another. This occurs as a result of bending of the wave which occurs since the mediums involved are of different density and refractive index.
Apart from the change in direction, refraction is accompanied by the change in wavelength of a wave and thus a change in speed.
Answer:
A. velocity and wavelength
Explanation:
An infected tooth forms an abscess (area of infected tissue) that fills with gas. The abscess puts pressure on the nerve of the tooth, causing a toothache. While waiting to see a dentist, the person with the toothache tried to relieve the pain by treating the infected area with moist heat. Will this treatment help? Why or why not?
Answer:
No, the treatment won't work
Explanation:
Since the abscess is filled with gas, and is already putting pressure on the tooth nerve, applying moist heat will only aggravate the problem. The pressure of a given gas increases with temperature and so, the gas within the abscess will only put more pressure on the nerve due to the expansion of the gas within the abcess, causing her more discomfort.
Sone one explain equilibrium to me what is it
Answer:
In econ: When supply and Demand are equal
Explanation:
Equilibrium is when something evens out
A car goes by 20 m/sec for 3 minutes. Find traveled distance?
HELP 25 POINTS MULTIPLE CHOICE
The energy due to the motion of an object is....
A)non mechanical B) potential C) thermal D) kinetic
Answer:
D) Kinetic.
Explanation:
Kinetic energy is energy in motion.
Answer: D
Explanation: kinetic is also called energy of motion , it is defined at the work needed to accelerate a body of a given mass from rest to its stated velocity.
HELP 75 POINTS ON THE LINE MULTIPLE CHOICE!
At the top of its arc, a thrown ball has ______ potential energy and _______kinetic energy.
A) zero, maximum
B) maximum, maximum
C) maximum, zero
D) minimum, maximum
Answer:
C
Explanation:
because at the top there is the greatest energy stored(potential energy)
so its maximum, and minimum
A painter on a ladder, painting the ceiling of a room comments. “It is hotter up here by the ceiling than it is down on the floor”. Explain why his observation is correct.
Answer:
1. Hot air is less dense and has moved upward allowing cool air to move downward which is less dens
(Convection current)
2. The ceiling has transferred heat to him by radiation.
Explanation:
During the day when air is heated as a result of the ceiling transferring heat to it, it becomes less dens and it gains energy, which make it lighter in weight than cooler air, this hot air moves upward allowing cooler air to move downward.
Help me out on this? Grades due in a couple days and I need to get everything done on time-
Answer:
75mL
...............
The question is full of inconsistencies and conceptual errors. Students should not waste their time trying to answer it ... it will only mislead and confuse them.
The question is poor. It was written by someone unclear on the concepts. It should be ignored.
Use the graph to answer the questions.
Based on the graph, what happens to current as resistance increases?
This type of graph shows which type of relationship between the two variables?
What would be a reasonable estimate for current at a resistance of 50 Ω?
Answer:
1) Decreases
2) Inverse Proportionality
3) 1 A
Explanation: Just Did Em'
Answer:
Decreases
Inverse Proportionality
1 A
Explanation:
correct on quiz EDGE2021
resonance occurs in an AC series circuit when which of the following condition is met ?
A,Resistant equal compactive resistance
B, comparative resistance equal zero
C, resistance equals inductive resistance
Answer:
capacitive reactance equals inductive reactance
A boat crosses a 200 m wide river at 3 ms-1, north relative to water. The river flows at 1 ms-1 as shown.
What is the velocity of the boat as observed by a stationary observer on the river back from which the boat departed?
Answer:
3.16 m·s⁻¹ at an angle of 71.6°
Explanation:
Assume that the diagram is like Fig. 1 below.
The boat is heading straight across the river and the current is directed straight downstream.
We have two vectors at right angles to each other.
1. Calculate the magnitude of the resultant
We can use the Pythagorean theorem (Fig. 2).
R² = (3 m·s⁻¹)² + (1 m·s⁻¹)² = 9 m²·s⁻² + 1 m²·s⁻² = 10 m²·s⁻²
R = √(10 m²·s⁻²) ≈ 3.16 m·s⁻¹
2. Calculate the direction of the resultant
The direction of the resultant is the counterclockwise angle (θ) that it makes with due East .
tanθ = opposite/adjacent = 3/1 = 3
θ = arctan 3 = 71.6°
To an observer at point O, the velocity of the boat is 3.16 m·s⁻¹ at an angle of 71.6°.
Two bicycle tires are set rolling with the same initial speed of 3.1 m/s m/s along a long, straight road, and the distance each travels before its speed is reduced by half is measured. One tire is inflated to a pressure of 40 psi psi and goes a distance of 19.0 m m ; the other is at 105 psi psi and goes a distance of 93.0 m m . Assume that the net horizontal force is due to rolling friction only and take the free-fall acceleration to be g gg = 9.8 m/ s 2 m/s2 . Part A What is the coefficient of rolling friction μ r μrmu_r for the tire under low pressure?
Answer:
Explanation:
From the formula
v² = u² + 2 a s , v is final velocity , u is initial velocity , a is acceleration and s is distance travelled .
u² / 4 = u² + 2 a x 19
- 3/4 u² = 2 a x 19
- (3 / 4) x 3.1² = 2 x 19 x a
a = - .18967 m /s²
deceleration due to friction = μg where g is acceleration due to gravity and μ is coefficient of friction .
a = μg
μ = a / g
= .18967 / 9.8
= .019 .
Avery took a wave motion rope and waved it sideways once. What kind of wave did Avery create, transverse, longitudinal, or a pulse?
Answer: transverse wave.
Explanation:
In a wave motion rope, the particles of the rope move in the perpendicular direction to the actual wave, so this is a transverse wave. (we have a longitudinal wave when the movement of the particles is in the same direction than the wave propagation, an example of this is the waves in the surface of the water when you throw a rock in)
Now, the fact that he waved it only once does not mean that this is a pulse if the other end of the rope is connected to a fixed point when the wave reaches that point will be reflected (losing a bit of amplitude, but we still will have a wave)
so the correct option is a transverse wave.
a student constructed a simple electric circuit where two light bulbs were connected in parallel. The circuit power source was a 6.0-V cell. One of the light bulbs had a resistance of 25 ohms, and the other had a resistance of 50 ohms. What was the combined resistance of the light bulbs in the circuit?
a) 75ohms
b) 42ohms
c) 25ohms
d) 17ohms
Answer:
RT = 17 ohms
Explanation:
For two parallel resistances in a circuit the combined resistance is given by:
[tex]\frac{1}{R_T}=\frac{1}{R_1}+\frac{1}{R_2}\\\\\frac{1}{R_T}=\frac{R_2+R_1}{R_1R_2}\\\\R_T=\frac{R_1R_2}{R_1+R_2}[/tex]
R1 = 25 ohms
R2 = 50 ohms
You replace the values of R1 and R2 in the formula for RT:
[tex]R_T=\frac{(25)(50)}{25+50}ohms=16.66\ ohms \approx 17\ ohms[/tex]
hence, the combined resitances is 17 ohms
A 50-kilogram object in outer space is attracted to a nearby planet with a
force of 400 newtons. What is the object's acceleration? *
Answer: 8m/s^2
Explanation:
By Newton's second law we have that.
F = m*a
Where F is force, m is mass and a is acceleration.
We know that m = 50kg and F = 400N
400N = 50kg*a
a = (400/50) m/s^2 = 8m/s^2
A uniform rod of length l and mass m rests on supports at its ends. The right support (white triangle) is quickly removed. a) What is the force from the left support immediately thereafter? A uniform rod of length 2r and moment of inertia rests on top of two supports, each of which is a distance d away from the center where is a constant. The right support (white triangle) is quickly removed. b) What is the force from the left support immediately thereafter?
Answer:
Explanation:
For solving this question we will be using Newton's second law of motion in 2 different formats.
F = ma and [tex]\tau = I\alpha[/tex]
Here F = net external force applied on the body
m = mass of the body
a = acceleration of the centre of mass of the body
[tex]\tau[/tex] = net external torque on the body
I = moment of inertia of the body about given axis
[tex]\alpha[/tex] = angular acceleration of the body
These are 2 forms of Newton's second law of motion first one is from transnational motion and second for rotational motion.
Kindly check the attached images below to see further step by step explanation to the question above.
a) Fill in the blanks in the following paragraph to correctly describe the nucleus of an atom.
_______ and _________ are the two types of nucleons that make up a nucleus. The __________ force exists between _________ in the nucleus because of their charge. Because it is repulsive, this force tends to make a nucleus __________. However, the __________ force acts between protons, between neutrons, and between protons and neutrons. This force helps to make a nucleus __________, because it is always attractive.
Answer:
Protons and Neutrons are the two types of nucleons that make up a nucleus. The electrostatic force exists between protons in the nucleus because of their charge. Because it is repulsive, this force tends to make a nucleus unstable. However, the strong nuclear force acts between protons, between neutrons, and between protons and neutrons. This force helps to make a nucleus stable, because it is always attractive.
Explanation:
The nucleus of an atom contains two types of particles, protons and neutrons. Proton has a positive charge, while neutron has no charge. The protons have a repulsive electrostatic force between each other, due to like charges. Due to this repulsive force protons tend to scatter away making the nucleus unstable. In order to overcome this, a force inside the nucleus binds these protons and neutrons together. This attractive force is called strong nuclear force. This force acts on very short ranges.
An atom is made up of nucleus and electrons orbitting the nucleus. The correct words are proton, neutron, electrostatic force, protons, unstable, nuclear, stable respectively.
Nucleus:
It is composed of Protons and Neutrons. Protons are potsitively charged , hence repulse each other which makes the nucleus unstable.
Nucleons held together by Strong nucleur force because it is the strongest force of universe.
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For each of the situations described below, the object considered is undergoing some changes. Among the possible changes you should consider are:
(Q) The object is absorbing or giving off heat.
(T) The object's temperature is changing.
(U) The object's internal energy is changing.
(W) The object is doing mechanical work or having work done on it.
(C) The objects chemical energy is changing.
For each of the situations described below, identify which of the four changes are taking place and write as many of the letters Q T U W C (or none) as are appropriate.
1. A cylinder with a piston on top contains a compressed gas and is sitting on a thermal reservoir (a large iron block). After everything has come to thermal equilibrium, the piston is moved upward somewhat (very slowly). The object to be considered is the gas in the cylinder.
Q T U W C
2. Consider the same cylinder as in part 1, but it is wrapped in styrofoam, a very good thermal insulator instead of sitting on a heat reservoir. The piston is pressed downward (again, very slowly), compressing the gas. The object to be considered is the gas in the cylinder.
Q T U W C
3. An ice cube sitting in the open air is melting.
Q T U W C
4. A mixture of two moles of hydrogen gas and one mole of oxygen gas in a thermally insulated vessel is subjected to small spark (contributing negligible energy) and converts to water vapor.
Q T U W C
Explain your reasoning for each of these cases.
Answer:
1.) Q T U W
Explanation:
1.) QTUW
2.) UW
3.) QU
4.) QTUC
According to first law of thermodynamics
dU = Q - W
Where
dU = change in internal energy
Q = heat added
W = work done by the system
2.) UW
Work is been done on the system. The pressure will surely distort the internal energy of the system
Pressure = Force/area.
3.) QU
The melting process begins because the air temperature around the ice cubes is warmer
The solid ice particles absorb heat energy from the warmer air, giving the particles energy and enabling them to move away from one another.
4.) Chemical reaction can be exothermic or endothermic which involves absorption or release of heat. Since it is subjected to small spark, there is definitely a change in internal energy.
In this exercise we have to have knowledge about thermodynamics in order to identify the alternatives that are correctly classified, so we can say that:
1.) QTUW
2.) UW
3.) QU
4.) QTUC
According to first law of thermodynamics:
[tex]dU = Q - W[/tex]
Where:
dU = change in internal energyQ = heat addedW = work done by the system1.) The first alternative corresponds to:
The object is absorbing or giving off heat.The object's temperature is changing.The object's internal energy is changing.The object is doing mechanical work or having work done on it.In other words QTUW.
2.) The second alternative corresponds to:
The object's internal energy is changing.The object is doing mechanical work or having work done on it.Work happen been finished ahead of the system. The pressure will without doubt deform the internal strength of bureaucracy:
[tex]Pressure = Force/area[/tex]
In other words UW.
3.) The third alternative corresponds to:
The object is absorbing or giving off heat.The object's internal energy is changing.The softening process begins cause the air coldness of some degree around the frozen water cubes happen warmer The complete frozen water particles take in heat strength from the warmer air, bestowing the piece energy and allowing to happen them to move out each one.
In other words QU.
4.) The fourth alternative corresponds to:
The object is absorbing or giving off heat.The object's temperature is changing.The object's internal energy is changing.The objects chemical energy is changing.Chemical reaction maybe exothermic or endothermic that involves assimilation or release of heat. Since it happen commit small spark, skilled happen certainly a change in within strength.
In other words QTUC
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A set of pulleys is used to lift a piano weighing 1,000 newtons. The piano is lifted 3 meters in 120 seconds. How much power was used?
Answer:
25 watts
Explanation:
Power=work/time
work=force x distance
1000 × 3
=3000 Joules
power= 3000/120
=25 watts
If A set of pulleys is used to lift a piano weighing 1,000 newtons. The piano is lifted 3 meters in 120 seconds. Then the power used is equal to 25 watts.
What is power?Power is the rate at which work is done or energy is transferred. It is a physical quantity that measures how quickly energy is used or transformed.
P=W/s
Where W= work done in joules.
s= time in seconds.
Power is typically measured in watts (W), which is equivalent to joules per second (J/s). In simple terms, power can be defined as the amount of work done or energy transferred per unit of time.
Here in the question,
To calculate the power used to lift the piano, we need to use the formula:
Power = Work / Time
The work done in lifting the piano is given by:
Work = Force x Distance
Where
Force = the weight of the piano, which is 1,000 newtons,
Distance = the height to which it is lifted, which is 3 meters.
Then, the work done is:
Work = 1,000 N x 3 m = 3,000 joules
The time taken to lift the piano is 120 seconds.
Now we can substitute these values in the formula for power:
Power = Work / Time
Power = 3,000 joules / 120 seconds
Power = 25 watts
Therefore, the power used to lift the piano is 25 watts.
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