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Ksju [112]
3 years ago
9

A 500-N box is pushed across a horizontal floor with a force of 250 N. The coefficient of kinetic friction is 0.4 Find the work

done in pushing the box 20 m. How much work went into overcoming friction and how much into accelerating the box?
Physics
1 answer:
lozanna [386]3 years ago
4 0

Answer:

Explanation:

W = Fd

work input to the box

W = 250(20) = 5000 J

work of friction

Wf = μ(mg)d = 0.4(500)(-20) = -4000 J

Kinetic energy change (accelerating the box)

5000 - 4000 = 1000 J

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An Object is located 16 cm in front of a converging lens with focal length 12 cm. To the right of the converging lens, separated
ExtremeBDS [4]

Answer:

image is located at 22.5cm to the left of diverging lens.

Explanation:

In this question we have given,

object distance from converging lens,u=-16cm

focal length of converging lens,f_{c}=12cm

focal length of diverging lens,f_{d}=-10cm

distance between converging and diverging lens=20cm

we have to find location of final image,v=?

Here we will first find the location of image formed by converging lens

we know that u, v and f_{c} are related by following formula

\frac{1}{f_{c}} =\frac{1}{v}- \frac{1}{u}.............(1)

put values of f_{c} and u in equation (1)

we got,

\frac{1}{12} =\frac{1}{v}- \frac{1}{-16}

\frac{1}{12}-\frac{1}{16} =\frac{1}{v}

\frac{16-12}{16\times 12} =\frac{1}{v}

or

v=\frac{16\times 12}{16-12}\\ v=48cm

The image is located 48 cm to the right of the converging lens. This image is real and inverted.

This  image will object for the diverging lens which is now located (48-20=18) cm at the right hand side of diverging lens

it means,

u=18cm

we know that u, v and f_{d} are related by following formula

\frac{1}{f_{d}} =\frac{1}{v}- \frac{1}{u}.............(2)

put values of f_{d} and u in equation (2)

\frac{1}{-10} =\frac{1}{v}- \frac{1}{18}

\frac{1}{-10}+\frac{1}{18} =\frac{1}{v}

\frac{-18+10}{10\times 18} =\frac{1}{v}

or

v=\frac{10\times 18}{10-18}\\ v=-22.5cm

It means image is located at 22.5cm to the left of diverging lens.

7 0
3 years ago
An object's buoyant force and weight mean the same thing.<br><br>A. True<br><br>B. False​
german

Answer:

False

Explanation:

No. The buoyant force on an object is the portion of its weight that appears to vanish

when the object is in any fluid (could be either a liquid or a gas).

If the object happens to float in a particular fluid, then the buoyant force at that moment

is equal to the object's weight.

Notice that the buoyant force on an object will be different in different fluids.

6 0
3 years ago
A cork floats on the surface of an incompressible liquid in a container exposed to atmospheric pressure. The container is then s
yaroslaw [1]

Question:

A cork floats on the surface of an incompressible liquid in a container exposed to atmospheric pressure. The container is then sealed and the air above the liquid is evacuated. The cork:

A. sinks slightly  

B. rises slightly  

C. floats at the same height  

D. bobs up and down about its old position

Answer:

The correct answer is C)  floats at the same height  

Explanation:

The liquid is incompressible because its density very high and leaves no room for further compaction whether or not there is atmospheric pressure. So when you put a cork on the liquid, pressure or no pressure, there is no displacement hence it floats on the same height regardless of the absence of air.

Cheers!

6 0
3 years ago
Astronomers study objects as large as galaxies. Chemists study objects that can be as small as an atom. Which of the following i
Inessa [10]

Answer:

A. both fields use the same technology

Explanation:

5 0
3 years ago
Read 2 more answers
If an object has two forces that are equal in magnitude, but acting on it in opposite directions, what are some possible things
Oksi-84 [34.3K]

Answer: The body will be in a position of rest

Explanation:

Since both forces are equal and acting in opposite direction on the body. It will make the body to be in a state of rest or equilibrium because the sum of the forces acting in the body will be zero.

5 0
3 years ago
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