A machinist with normal vision has a near point at 25 cm. This machinist wears +4.25-diopter eyeglasses in order to do very close work. With these eyeglasses, what is the near point of the machinist?
a. 12 cm
b. 10 cm
c. 7 cm
d. 15 cm
e. 17 cm
Answer: 12cm.
Explanation:
First we need to calculate the focal length which will be:
= 100 / 4.25
= 23.529
The near point of the machinist will be solved using the equation:
1/u + 1/v = 1/f
where,
v = -25
f = 23.529
1/u + 1/v = 1/f
1/u - 1/25 = 1/23.529
1/u = 1/23.529 + 1/25
u = 12.12cm
u = 12cm approximately
Therefore, the near point of the machinist is 12cm
If an object has a mass of 47 kg and it is moved 27 meters in 60 seconds, how much power was used?
Answer: 207 W
Explanation: I assumed here that the object is moved vertically. If that is the case, the work done on the object is equal to its change in gravitational potential energy:
where
m = 47 kg is the mass of the object
g = 9.8 m/s^2 is the acceleration of gravity
is the change in height
Substituting,
Now we can calculate the power used, which is given by
Hope this helps I'm sorry if i'm wrong but I tried :(
Light of wavelength 400 nm falls on a metal surface having a work function 1.70 eV. What is the maximum kinetic energy of the photoelectrons emitted from the metal?
a. 4.52 eV
b. 3.11 ev
c. 141 eV
d. 2.82 eV
e. 1.70 eV
Answer:
Ke = 1.41 eV
Explanation:
We know that
h = 6.626 x 10⁻²⁴
c = 3 x 10⁸
λ = 4 x 10⁻⁹ x 1.6 x 10⁻¹⁹
Computation:
Ke = [hc / λ] - w
Ke = [(6.626 x 10⁻²⁴)(3 x 10⁸) / (4 x 10⁻⁹ x 1.6 x 10⁻¹⁹)] - 1.70
Ke = 1.41 eV
What form of energy is released into the atmosphere by the earth's surface
Answer:
Thermal Energy (Heat)
Answer:
Heat
Explanation:
the form that is raised from the atmosphere from earths surface is heat
A metallic spherical shell has a charge density of 1 mC/m2 on its surface. The shell has radius of 7.5 cm. Determine the electric field magnitude (in kV/m) 10 meters away from the center of the shell.
Answer:
Explanation:
charge on the shell = 4πR² x charge density
= 4 x 3.14 x 7.5² x 10⁻⁴ x 10⁻³ C
= 706.5 x 10⁻⁷ C
electric field = k Q / d² , d is distance of point from centre
= 9 x 10⁹ x 706.5 x 10⁻⁷ / 10²
= 6358.5 N /C
= 6.358 kV / m
If the light ray moves from inside the glass toward the glass–air interface at an angle of 30.0° to the normal, determine the angle of refraction.
Answer:
This question is incomplete
Explanation:
This question is incomplete, however, the relationship to between the angle of incidence and angle of refraction is best explained by snell's law with the equation below
ni sinθi = nr sinθr
where ni is the refractive index of the incident medium (assuming it's plate glass then 1.52)
nr is the refractive index of the refractive medium (1.33)
θi is the angle of incidence (30°)
θr is the angle of refraction (X)
If we substitute the values, we have
1.52 × sin 30 = 1.33 × sin X
1.52 × 0.5 = 1.33 × sin X
0.75 = 1.33 × sin X
sin X = 0.75/1.33
sin X = 0.571
X = sin⁻¹ 0.571
X = 34.82°
Thus, the angle of refraction will be 34.82°
A 65-turn coil has a diameter of 14 cm. Find the magnitude of the emf induced in the coil (in V) if it is placed in a spatially uniform magnetic field of magnitude 0.65 T so that the face of the coil makes the following angles with the magnetic field, and the magnetic field is reduced to zero uniformly in 0.2 s.
Answer:
The value is [tex]\epsilon = 3.24 \ V[/tex]
Explanation:
From the question we are told that
The number of turns is n = 65
The diameter is [tex]d = 14 \ cm = 0.14 \ m[/tex]
The magnetic field is [tex]B_1 = 0.65 \ T[/tex]
The time taken for the magnetic field to be reduced to [tex]B_2 = 0 \ T[/tex] is [tex]\Delta t = 0.2 s[/tex]
Generally the magnitude of the induced emf is mathematically represented as
[tex]\epsilon = N * \frac{B_1 - B_2}{\Delta t } * A[/tex]
Here A is the area of the coil which is mathematically represented as
[tex]A = \pi * \frac{d^2}{4}[/tex]
=> [tex]A = 3.142 * \frac{0.14^2}{4}[/tex]
=> [tex]A = 0.0154 \ m^2[/tex]
So
[tex]\epsilon = 65 * \frac{0.65 - 0 }{0.2 } * 0.01534[/tex]
=> [tex]\epsilon = 3.24 \ V[/tex]
what are fundamental quantities
Answer: length, luminous intensity,mass, time, temperature, electric current, amount of a substance.
Explanation:
I need help ASAP
The water cycle functions because the matter in water changes:
a.forms
b.properties
c.minerals
Answer:
(a). forms.
Explanation:
Bro even i ain't sure.
Answer:
I think its A? Because in the water cycle it goes from a liquid to a gas?
Explanation:
At the focal point of a converging lens, the object cannot be seen. O A. True B. False
Answer: True
Explanation: Guessed on A p E x and it was correct
Answer:
True
Explanation:
a p e x
A student puts a besker of warm water next to a besker of cold water so that they fough which two statements are true? DA Thermal energy will move from the warm water to the cold water Thermal energy will move from the air to the cold water. Thermal energy utill move from the air to the warm water Thermal energy till move from the cold water to the warm water
Explanation:
so sorry
don't know but please mark me as brainliest please
Which dwarf planet has a moon nearly as large as itself?
Answer:
The answer is the Pluto.
For a 99 kg person standing at the equator, what is the magnitude of the angular momentum about Earth's center due to Earth's rotation?
Answer:
L = 4.58 x 10⁴ kg.m²/s
Explanation:
The angular momentum is given by the formula:
L = mvr
but, v = rω
Therefore,
L = mr²ω
where,
L = Angular Momentum of the person = ?
m = mass of person = 99 kg
r = radius of earth = 6.37 x 10⁶ m
ω = Angular Speed of Earth's Rotation = θ/t
Since, earth completes 1 rotation in 1 day. Hence,
ω = (2π rad/1 day)(1 day/24 h)(1 h/3600 s)
ω = 7.27 x 10⁻⁵ rad/s
Therefore,
L = (99 kg)(6.37 x 10⁶ m)²(7.27 x 10⁻⁵ rad/s)
L = 4.58 x 10⁴ kg.m²/s
While Barb was playing soccer, she was kicked in the anterior thigh by an opposing teammate. Due to this injury, what muscle function may she find difficult to perform?
Answer:
knee extension is the muscle function that will be difficult to perform.
Explanation:
Barb was kicked in the anterior thigh. Now, the thigh muscles performs a combined operation of moving the knee and leg and they reside in the following compartments.
- Anterior compartment which is composed of knee joint extension and thigh flexion.
- Lateral Compartment which is composed of the tensor fasciae latae, which is a tiny muscle that abducts and centrally will make the thigh to rotate.
-Medial compartment which involves thigh addiction which is rotating of the thigh around the hips.
- Posterior compartment which involves knee joint flexion and high extension.
Thus, from the different compartments listed above, we can see that the muscles that extend the knee and flex the thigh all lie in the anterior compartment of the upper leg.
Thus, we can conclude that knee extension is the muscle function that will be difficult to perform.
frequency of a vibrating string with a period of 4 seconds
Answer: 2 Hz (8 cycles/4 s = 2 cycles/s).
Explanation:
If a coil of slinky makes 3 vibrational cycles in one second, then the frequency is 3 Hz. And if a coil makes 8 vibrational cycles in 4 seconds, then the frequency is 2 Hz (8 cycles/4 s = 2 cycles/s).
please help im failing!!!
n an experiment of a simple pendulum, measurements show that the pendulum has length m, mass kg, and period s. Take m/s2 . i. Use the measured length to predict the theoretical pendulum period with a range of error (use the error propagation method you learned in Lab 1). ii. Compute the percentage difference (as defined in Lab 1) between the measured value and the predicted value .
Answer:
The answer is "[tex](1.265 \pm 0.010) \ s \ and \ 0.709 \%[/tex]"
Explanation:
In point i:
[tex]T_{theo}= 2\pi \sqrt{\frac{l}{g}}[/tex]
[tex]=2\pi\sqrt{\frac{0.397}{9.8}}\\\\= 1.265 \ s[/tex]
If error in the theoretical time period :
[tex]\frac{\Delta T_{theo}}{T_theo} = \frac{1}{2} \frac{\Delta l }{l}\\\\\Delta T_{theo} = 1.265 \times \frac{1}{2} \times \frac{0.006}{0.397}[/tex]
[tex]= 0.010 \ s[/tex]
[tex]T_{theo} = (1.265 \pm 0.010) \ s[/tex]
In point ii:
[tex]\% \ difference = \frac{|T_{exp} -T_{theo}|}{\frac{T_{exp}+T_{theo}}{2}} \times 100[/tex]
[tex]= \frac{1.274 -1.265}{\frac{1.274+1.265}{2}} \times 100\\\\=0.709 \%[/tex]What is a possible equation fir an ionic compound with calcium
Answer:
CaO, CaMg, or CaF2
Ca2Cl, CaNa, or CaP
CaF, CaMg, or CaNa
CaO, CaF2, or CaCl2
Explanation: i think
The density for gold is 19.3 g/cm3. What would be the mass of a 45 cm3 piece of gold?
Answer:
868.5 g
Explanation:
Mass= Density x Volume
Mass= 19.3 x 45
=868.5
Answer:
675.5g
Explanation:
The formula for density is: D = m/V.
To solve this problem, we need to rearrange this formula to solve for mass:
m = D x V.
Next, we plug the given values in for density, D, and volume, V:
m = 19.3 g/cm3 x 35 cm3
So, m = 675.5 g
Someone help me please.
Answer:
ionic
ionic
covalent
covalent (i think)
Explanation:
ionic= donate electrons (gain/lose)... (results in ions that have +/- charge, are no longer neutral)
covalent= share electrons
I need help with this science work
Please tell us the question and we will try to answer.
A particle with charge q and mass m moving with speed v in the x direction enters a magnetic field of strength B pointing in the y direction. The magnitude of the acceleration of the particle as it travels one semicircle is
Answer:
The acceleration of the particle as it travels one semicircle is
[tex]a= \frac{\pi R}{t^2}[/tex]
Explanation:'
Kindly see attached a sketch of a semi-circle
Step one:
given data
velocity =v
let the time taken be t
The path PQM is the distance covered
so distance [tex]d= \pi R[/tex]
we know that time= distance/velocity
t= πR/v
step two:
velocity =distance/time
[tex]velocity=\frac{\pi R}{t}[/tex]
also, we know that acceleration is velocity/time
[tex]a= \frac{\pi R}{\frac{t}{t} }[/tex]
[tex]a= \frac{\pi R}{t}*\frac{1}{t}[/tex]
[tex]a= \frac{\pi R}{t^2}[/tex]
Two men, Joel and Jerry, push against a wall. Jerry stops after 10 min, while Joel is able 1) to push for 5.0 min longer. Compare the work they do. A) Both men do positive work, but Joel does 25% more work than Jerry. B) Both men do positive work, but Joel does 75% more work than Jerry. C) Both men do positive work, but Jerry does 50% more work than Joel. D) Both men do positive work, but Joel does 50% more work than Jerry E) Neither of them does any work.
Answer:
the correct answer is E
Explanation:
Work is defined by the expression
W = F. d
Where the bold indicates vectors, we can make the dot product explicit
W = F d cos θ
We can see that this definition of work the two men apply a force, but the wall does not move, so if there is no displacement the work is zero.
When checking the correct answer is E
Under what conditions the reaction rate of an enzymolysis that follows Michaelis-Menten kinetics is a quarter of its maximum value?
a. [S]=KM
b. [S]=KM/3
c. [S]=2KM
d. [S]=KM+3
e. [S]= (KM)^1/3
Solution :
Michaelis-Menten kinetics in the field of biochemistry is considered as one of the well known models for enzyme kinetics. The model represents an equation that describes the enzymatic reactions's rate by relating the reaction rate to the substrate's concentration. The equation is named after the two famous scientists, Leonor Michaelis and Maud Menten.
The formula is :
[tex]$v=\frac{V_{max}[S]}{K_M + [S]}$[/tex]
where v = velocity of reaction
[tex]$V_{max}$[/tex] = maximum rate achieved
[tex]$K_M$[/tex] = Michaelis constant
[S] = concentration of the substrate, S
According to the question, by putting the velocity of reaction, v as [tex]$\frac{V_{max}}{4}$[/tex], we get the above equation as
[tex]$[S]= \frac{K_M}{3}$[/tex]
Therefore the answer is [tex]$[S]= \frac{K_M}{3}$[/tex]
People have been able to make materials such as fiber optics cables A. using nails and screws. B. using glue and scissors. C. using rocks and stones. D. using science and technology.
Answer:
D
Explanation:
Calculate the pressure in pascals if a 560N is applied to an area of 1.6m².
Answer:
P = 350 [Pa]
Explanation:
The pressure is calculated by knowing the force and area. By means of the following formula can be calculated by means of the following equation.
Units of 1 [Pa] = 1 [N/m²]
P = F/A
where:
P = pressure [Pa]
F = force = 560 [N]
A = area = 1.6 [m²]
P = 560/1.6
P = 350 [Pa]
This is a graph of a car speeding up and then reaching a constant speed of 105 m/s . After it finishes speeding up, how far does the car travel during the last 6 seconds of the graph, from 4 to 10 s?
60 m
Explanation:Concept Used:
We know that the area under a velocity-time graph represents the Displacement of the body
Displacement in the Last 6 seconds:
To find the Displacement in the last 6 seconds, we will find the area under the graph between x = 4 and x = 10
We can see that the shape formed is a rectangle also shown in the given graph. So, the area of the rectangle is the Displacement of the car in the last 6 seconds
Area of the Rectangle:
From the graph, we know that the rectangle is 10 (m/s) tall and 6 (s) wide
Area of Rectangle= length*Breadth
replacing the values
Area = 10 (m/s) * 6 (s)
Area = 60 m
Hence, the car travelled 60 m in the last 6 seconds of the graph
When a satellite is in orbit around the Earth, the force of the gravity on the satellite is...
Answer:
Is always towards the center of the Earth
Explanation:
A copper block rests 17.4 cm from the center of a steel turntable. The coefficient of static friction between block and surface is 0.465. The turntable starts from rest and rotates with a constant angular acceleration of 0.406 rad/s 2 . The acceleration of gravity is 9.8 m/s 2 . After what interval will the block start to slip on the turntable
Answer:
12.61 s
Explanation:
Given that
Distance from the center if the turntable, r = 17.4 cm = 0.174 m
Coefficient of static friction, μ = 0.465
Angular acceleration, α = 0.406 rad/s²
Acceleration due to gravity, g = 9.8 m/s²
We know that
F_max = μmg
Also, we know that
F = mω²r
Now, for slip to occur, both forces must be equal to one another, and thus
mω²r = μmg
ω²r = μg
ω² = μg/r
ω² = (0.465 * 9.8)/0.174
ω² = 4.557 / 0.174
ω² = 26.19
ω = √26.19
ω = 5.12 rad/s
t = ω/α
t = 5.12/0.406
t = 12.61 s.
Thus, after 12 seconds, the block will start to slip on the turntable
Imagine holding two identical bricks under water. Brick A is just beneath the surface of the water, while brick B is at a greater depth. What is the force needed to hold brick B in place? (Assume the density of water doesn't change with height.) a) the same as b) larger c) smaller than the force required to hold brick A in place.
Answer:
I think it's c
Explanation:
The brick's mass, helps to hold it under the water but brick A is being held up. If you dropped the brick, it would sink to the bottom. You need a stronger force to hold it up.
Hope this helps you! x
Buoyancy force is needed to hold brick B in place.
What is force?
A force is an effect that can alter an object's motion according to physics. An object with mass can change its velocity, or accelerate, as a result of a force. An obvious way to describe force is as a push or a pull. A force is a vector quantity since it has both magnitude and direction.
Upthrust, often known as buoyancy, is an upward force applied by a fluid against the weight of an object that is partially or completely submerged. The weight of the fluid on top causes pressure in a fluid column to rise with depth. The brick's mass, helps to hold it under the water but brick A is being held up. If you dropped the brick, it would sink to the bottom. You need a stronger force to hold it up.
Buoyancy force is needed to hold brick B in place.
To learn more about force refer to the link:
brainly.com/question/13191643
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