Question 1

A 1.5 kg book rests on a table. What is the magnitude of the normal force exerted by the table on the book? (Assume $$g = 9.8\ \mathrm{m/s^2$}$$ and the table is horizontal.)

Accepted Answer

$$14.7\ \mathrm{N}$$

Question 2

A car is being pushed at a constant speed across a level road. Which statement best explains why the car does not accelerate?

Accepted Answer

The net force on the car is zero because the pushing force and friction force are equal in magnitude and opposite in direction.

Question 3

A 2.0 kg block is pulled with a constant force, causing it to accelerate at $$3.0\ \mathrm{m/s^2$}. $$What is the magnitude of the pulling force?

Accepted Answer

$$6.0\ \mathrm{N}$$

Question 4

A skydiver reaches terminal velocity during free fall. Which of the following is true about the forces acting on her?

Accepted Answer

The net force is zero.

Question 5

A 10 kg box is pulled by a rope with a tension of $$50\ \mathrm{N} at an $$angle of $$30^\circ$$ above the horizontal. If the box moves at constant velocity, what is the magnitude of the friction force?

Accepted Answer

$$43.3\ \mathrm{N}$$

Question 6

A ball is thrown straight up. Ignore air resistance. What is the only force acting on the ball just after it leaves the thrower's hand?

Accepted Answer

The force of gravity (weight)

Question 7

A 5.0 kg object is acted on by two forces: $$\vec{F}_1 = 10\ \mathrm{N} to $$the right and $$\vec{F}_2 = 6\ \mathrm{N} to $$the left. What is the acceleration of the object?

Accepted Answer

$$0.8\ \mathrm{m/s^2$}$$\ to\ the\ right

Question 8

A person stands motionless on a bathroom scale. Which forces act on the person?

Accepted Answer

Weight force and normal force

Question 9

A mosquito collides head-on with a moving truck. According to Newton’s third law, during the collision:

Accepted Answer

The mosquito and the truck exert equal and opposite forces on each other.

Question 10

A 60 kg skier is being towed up a frictionless hill at a constant speed by a rope. What is the net force acting on the skier?

Accepted Answer

$$0\ \mathrm{N}$$

Question 11

A block is pulled with a constant force and moves with a constant acceleration. If the mass of the block is doubled, what happens to its acceleration?

Accepted Answer

It is halved.

Question 12

A 1000 kg elevator is lifted upward with a constant acceleration of $$2.0\ \mathrm{m/s^2$}. $$What is the tension in the cable? (Take $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$11,800\ \mathrm{N}$$

Question 13

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 14

A block is at rest on a horizontal surface. Which of the following statements is correct?

Accepted Answer

The normal force is equal in magnitude and opposite in direction to the weight.

Question 15

A 3.0 kg object is acted on by a net force of $$12\ \mathrm{N} to $$the right. What is its acceleration?

Accepted Answer

$$4.0\ \mathrm{m/s^2$}$$\ to\ the\ right

Question 16

A person pushes a box across a rough floor at a steady speed. Which of the following is true about the forces acting on the box?

Accepted Answer

The pushing force and friction force are equal in magnitude and opposite in direction.

Question 17

A 2.0 kg block is pulled by a spring with a force of $$8.0\ \mathrm{N}. $$What is the acceleration of the block?

Accepted Answer

$$4.0\ \mathrm{m/s^2$}$$

Question 18

A 40-car train travels at a constant speed on a straight track, while a skier speeds up as she skis downhill. On which is the net force greater?

Accepted Answer

The skier

Question 19

A block is pulled to the right with a constant, steady force. How will its acceleration graph look?

Accepted Answer

A constant, nonzero value

Forces and Newton’s Laws of Motion: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard