Question 1

A 70 kg person stands on a scale in an elevator accelerating upward at 2 m/s². What does the scale read?

Accepted Answer

$$826\ \mathrm{N}$$

Question 2

A 100 kg block hangs from a rope. If the block is moving upward at a constant speed, what is the tension in the rope?

Accepted Answer

$$1000\ \mathrm{N}$$

Question 3

A car of mass $$1500\ \mathrm{kg} is $$towed at a steady speed by a rope at an angle. The friction force is $$320\ \mathrm{N}. $$What is the horizontal component of the tension in the rope?

Accepted Answer

$$320\ \mathrm{N}$$

Question 4

Which of the following statements about static and kinetic friction is correct?

Accepted Answer

The coefficient of static friction is generally greater than the coefficient of kinetic friction.

Question 5

A 1.2 kg book lies on a table. If a 15 N downward force is applied on top of the book, what is the normal force from the table?

Accepted Answer

$$26.8\ \mathrm{N}$$

Question 6

A skier slides down a frictionless slope inclined at $$30^\circ. $$What is the skier’s acceleration?

Accepted Answer

$$a = g \sin 30^\circ$$

Question 7

A 32 kg sofa is pushed at a steady speed across the floor with a coefficient of kinetic friction $$\mu_k = 0.08. $$What is the force required to keep it moving?

Accepted Answer

$$25\ \mathrm{N}$$

Question 8

A 50 kg student stands on a scale in a falling elevator after the cable breaks. What does the scale read?

Accepted Answer

$$0\ \mathrm{N}$$

Question 9

A 75 kg skydiver reaches terminal speed when the drag force equals their weight. If $$g = 9.8\ \mathrm{m/s^2$}$$, what is the drag force at terminal speed?

Accepted Answer

$$735\ \mathrm{N}$$

Question 10

A block is pulled to the right at steady speed by a rope that angles upward. How does the normal force compare to the block’s weight?

Accepted Answer

$$n \u003c m g$$

Question 11

A 20 kg sled slides at $$4.5\ \mathrm{m/s}$$ onto snow with a friction force of $$12\ \mathrm{N}. $$How far does it slide before stopping?

Accepted Answer

$$33.8\ \mathrm{m}$$

Question 12

A 5 kg block A is pushed with a 3 N force against a 10 kg block B. Both move together on a frictionless surface. What force does A exert on B?

Accepted Answer

$$2\ \mathrm{N}$$

Question 13

A 200 kg stage set is attached to a 100 kg stagehand by a rope over a massless, frictionless pulley. What is the acceleration of the system?

Accepted Answer

$$a = \frac{(200 - 100)g}{200 + 100}$$

Question 14

A box is at rest on a rough surface. A 30 N horizontal force is applied, but the box does not move. What can you conclude?

Accepted Answer

The maximum static friction force is at least 30 N.

Question 15

A ball weighing 50 N is pulled back by a rope at an angle. What is the tension in the rope if the ball is stationary?

Accepted Answer

Greater than 50 N

Question 16

A box is being pulled to the right over a rough surface and the rope breaks. What happens to the box?

Accepted Answer

It slows steadily until it stops.

Question 17

Which of the following is true about the tension in a massless rope passing over a massless, frictionless pulley?

Accepted Answer

The tension is the same at all points in the rope.

Question 18

A 4.8 kg penguin glides in water at 1.6 m/s and slows with acceleration $$-0.15\ \mathrm{m/s^2$}. If $$the drag force is $$F_D = \frac{1}{2} C \rho A v^2$, what is the drag force at this speed?

Accepted Answer

$$0.72\ \mathrm{N}$$

Chapter 5: Applying Newton’s Laws – Structured Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards