Question 1

A person pushes a stalled car with a force of $$400\ \mathrm{N}$$ over a distance of $$20\ \mathrm{m} in $$the direction of the force. How much work is done by the person on the car?

Accepted Answer

$$8000\ \mathrm{J}$$

Question 2

Which of the following statements about kinetic energy is correct?

Accepted Answer

Kinetic energy is a scalar quantity and depends only on the mass and speed of the object.

Question 3

A $$2\ \mathrm{kg}$$ object is moving at $$3\ \mathrm{m/s}. $$What is its kinetic energy?

Accepted Answer

$$18\ \mathrm{J}$$

Question 4

A force of $$50\ \mathrm{N}$$ acts at an angle of $$60^{\circ} to $$the direction of displacement of $$4\ \mathrm{m}. $$What is the work done by the force?

Accepted Answer

$$100\ \mathrm{J}$$

Question 5

Which scenario results in zero work being done by a force?

Accepted Answer

A force is applied perpendicular to the displacement.

Question 6

A $$5\ \mathrm{kg}$$ box is lifted vertically upward $$2\ \mathrm{m} at $$constant speed. What is the work done by gravity?

Accepted Answer

$$-100\ \mathrm{J}$$

Question 7

A spring with force constant $$k = 200\ \mathrm{N/m} is $$stretched $$0.10\ \mathrm{m}$$ from its equilibrium position. What is the work done to stretch the spring?

Accepted Answer

$$2\ \mathrm{J}$$

Question 8

A $$1000\ \mathrm{kg}$$ car accelerates from rest to $$20\ \mathrm{m/s}. $$What is the change in its kinetic energy?

Accepted Answer

$$200,000\ \mathrm{J}$$

Question 9

Which of the following best describes the work-energy theorem?

Accepted Answer

The work done by the net force on a particle equals the change in the particle's kinetic energy.

Question 10

A $$0.1\ \mathrm{kg}$$ glider is attached to a spring ($$k = 20\ \mathrm{N/m}) $$and moves at $$1.5\ \mathrm{m/s} on a $$frictionless air track. What is the maximum distance the spring will stretch before the glider stops?

Accepted Answer

$$0.0169\ \mathrm{m}$$

Question 11

A $$10\ \mathrm{kg}$$ box is pulled across a horizontal floor by a force of $$50\ \mathrm{N} at$$ $$30^{\circ}$$ above the horizontal for $$5\ \mathrm{m}. $$What is the work done by the force?

Accepted Answer

$$216.5\ \mathrm{J}$$

Question 12

If a $$1\ \mathrm{N}$$ apple is lifted $$1\ \mathrm{m} at $$constant speed, what is the work done on the apple?

Accepted Answer

$$1\ \mathrm{J}$$

Question 13

A $$3\ \mathrm{kg}$$ object moves in a circle of radius $$2\ \mathrm{m} at $$constant speed. What is the work done by the centripetal force after one complete revolution?

Accepted Answer

$$0\ \mathrm{J}$$

Question 14

A $$60\ \mathrm{kg}$$ person climbs a $$5\ \mathrm{m}$$ high staircase in $$10\ \mathrm{s}. $$What is the average power output against gravity?

Accepted Answer

$$294\ \mathrm{W}$$

Question 15

Which of the following is true about the dot product in the context of work?

Accepted Answer

It projects one vector onto another, giving the amount of force along the direction of displacement.

Question 16

A $$10\ \mathrm{kg}$$ box is pushed with a constant force of $$40\ \mathrm{N}$$ over $$5\ \mathrm{m}$$, but friction opposes the motion with $$10\ \mathrm{N}. $$What is the net work done on the box?

Accepted Answer

$$150\ \mathrm{J}$$

Question 17

A $$2\ \mathrm{kg}$$ object moving at $$4\ \mathrm{m/s} is $$brought to rest by a constant force over $$8\ \mathrm{m}. $$What is the magnitude of the force?

Accepted Answer

$$2\ \mathrm{N}$$

Question 18

Which of the following is the correct expression for instantaneous power delivered by a force $$\vec{F}$$ acting on a particle with velocity $$\vec{v}$$?

Accepted Answer

$$P = \vec{F} \cdot \vec{v}$$

Question 19

A $$0.5\ \mathrm{kg}$$ ball is thrown straight up with an initial speed of $$10\ \mathrm{m/s}. $$What is its kinetic energy at the highest point?

Accepted Answer

$$0\ \mathrm{J}$$

Work and Kinetic Energy – University Physics Chapter 6 Study Notes

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