Q: A jet engine produces a constant thrust to accelerate a plane of mass $$m$$ from rest to speed $$v$$ over a distance $$d. $$Which equation would you use to find the net force if the acceleration is constant?

$$\vec{F}_{\text{net}} = m \vec{a}$$

Question 1

A car of mass $$m is $$moving at a constant velocity on a straight, level road. Which of the following statements is correct about the net force acting on the car?

Accepted Answer

The net force is zero: $$\sum \vec{F} = 0.$$

Question 2

A 2 kg block is pulled by a rubber band with a constant force, resulting in an acceleration of $$3\ \mathrm{m/s^2$}. If $$the same force is applied to a 1 kg block, what will be its acceleration?

Accepted Answer

$$6\ \mathrm{m/s^2$}$$

Question 3

Which of the following best describes the direction of the normal force acting on a skier going down an inclined slope?

Accepted Answer

Perpendicular to the surface of the slope

Question 4

A box is at rest on a horizontal table. Which forces act on the box?

Accepted Answer

Weight and normal force

Question 5

A jet engine produces a constant thrust to accelerate a plane of mass $$m$$ from rest to speed $$v$$ over a distance $$d. $$Which equation would you use to find the net force if the acceleration is constant?

Accepted Answer

$$\vec{F}_{	ext{net}} = m \vec{a}$$

Question 6

A block is pulled across a rough surface at constant speed. Which statement is true about the forces acting on the block?

Accepted Answer

The pulling force is equal to the friction force.

Question 7

A bungee jumper is at the lowest point of her jump, momentarily at rest. Which forces act on her at this instant?

Accepted Answer

Weight and tension

Question 8

A leaf falls from a tree and reaches terminal velocity. Which statement best describes the forces acting on the leaf?

Accepted Answer

The drag force equals the weight of the leaf.

Question 9

A rocket expels exhaust gases downward. According to Newton’s third law, what is the direction of the thrust force on the rocket?

Accepted Answer

Upward

Question 10

A 1 kg block is pulled with a force of 10 N. What is its acceleration?

Accepted Answer

$$10\ \mathrm{m/s^2$}$$

Question 11

A car is moving at 15 m/s and a runner is moving at 5 m/s in the same direction. What is the speed of the car relative to the runner?

Accepted Answer

10 m/s

Question 12

Which of the following is NOT a contact force?

Accepted Answer

Weight

Question 13

A block is at rest on a table. If the table is suddenly removed, what will happen to the block?

Accepted Answer

It will accelerate downward due to gravity.

Question 14

If the net force on an object is zero, which of the following must be true?

Accepted Answer

The object moves with constant velocity or remains at rest.

Question 15

A block is pulled by two forces: $$\vec{F}_1 = 5\ \mathrm{N} to $$the right and $$\vec{F}_2 = 3\ \mathrm{N} to $$the left. What is the net force on the block?

Accepted Answer

$$2\ \mathrm{N} to $$the right

Question 16

A 60 kg astronaut in space pushes on a 120 kg satellite. If the astronaut moves backward at 2 m/s, what is the velocity of the satellite?

Accepted Answer

$$1\ \mathrm{m/s} in $$the opposite direction

Question 17

A block is sliding down a ramp inclined at angle $$	heta. $$Which component of the gravitational force causes the block to accelerate down the ramp?

Accepted Answer

$$mg \sin 	heta$$

Question 18

Which of the following best describes static friction?

Accepted Answer

It prevents an object from starting to move.

Question 19

A block is pulled with a force $$F$$ and accelerates at $$a. If $$the mass of the block is doubled and the same force is applied, what is the new acceleration?

Accepted Answer

$$a/2$$

Question 20

Which of the following is the correct SI unit for force?

Accepted Answer

Newton (N)

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