Chapter 5, The Laws of Motion Video Solutions, Physics for Scientists and Engineers With Modern Physics

Problem 1

A passenger sitting in the rear of a bus claims that he was injured when the driver slammed on the brakes, causing a suitcase to come flying toward the passenger from the front of the bus. If you were the judge in this case, what disposition would you make? Why?

Jennifer Stoner

Numerade Educator

04:00

Problem 2

A space explorer is in a spaceship moving through space far from any planet or star. She notices a large rock, taken as a specimen from an alien planet, floating around the cabin of the spaceship. Should she push it gently toward a storage compartment or kick it toward the compartment? Why?

Vishal Gupta

Numerade Educator

03:02

Problem 3

A massive metal object on a rough metal surface may undergo contact welding to that surface. Discuss how this affects the frictional force between object and surface.

Sachin Rao

Numerade Educator

03:54

Problem 4

The observer in the elevator of Example 5.8 would claim that the weight of the fish is $T$, the scale reading. This claim is obviously wrong. Why does this observation differ from that of a person in an inertial frame outside the elevator?

Averell Hause

Carnegie Mellon University

02:25

Problem 5

Identify the action-reaction pairs in the following situations: a man takes a step; a snowball hits a woman in the back; a baseball player catches a ball; a gust of wind strikes a window.

Massimo Antonelli

Numerade Educator

01:33

Problem 6

A ball is held in a person's hand. (a) Identify all the external forces acting on the ball and the reaction to each. (b) If the ball is dropped, what force is exerted on it while it is falling? Identify the reaction force in this case. (Neglect air resistance.)

Esmaeil Mahdavi

Numerade Educator

01:45

Problem 7

If a car is traveling westward with a constant speed of $20 \mathrm{~m} / \mathrm{s}$, what is the resultant force acting on it?

Jerrah Biggerstaff

Numerade Educator

05:51

Problem 8

"When the locomotive in Figure 5.3 broke through the wall of the train station, the force exerted by the locomotive on the wall was greater than the force the wall could exert on the locomotive." Is this statement true or in need of correction? Explain your answer.

Zulfiqar Ali

Numerade Educator

02:54

Problem 9

A rubber ball is dropped onto the floor. What force causes the ball to bounce?

Sheh Lit Chang

University of Washington

01:26

Problem 10

What is wrong with the statement, "Because the car is at rest, no forces are acting on it"? How would you correct this statement?

Jerrah Biggerstaff

Numerade Educator

03:45

Problem 11

Suppose you are driving a car along a highway at a high speed. Why should you avoid slamming on your brakes if you want to stop in the shortest distance? That is, why should you keep the wheels turning as you brake?

Nicholas Majtenyi

Numerade Educator

01:03

Problem 12

If you have ever taken a ride in an elevator of a high-rise building, you may have experienced a nauseating sensation of "heaviness" and "lightness" depending on the direction of the acceleration. Explain these sensations. Are we truly weightless in free-fall?

Km Neeraj

Numerade Educator

01:50

Problem 13

The driver of a speeding empty truck slams on the brakes and skids to a stop through a distance $d$. (a) If the truck carried a heavy load such that its mass were doubled, what would be its skidding distance? (b) If the initial speed of the truck is halved, what would be its skidding distance?

Manish Kumar

Numerade Educator

01:04

Problem 14

In an attempt to define Newton's third law, a student states that the action and reaction forces are equal in magnitude and opposite in direction to each other. If this is the case, how can there ever be a net force on an object?

Aakash Ramachandran

Numerade Educator

02:09

Problem 15

What force causes (a) a propeller-driven airplane to move? (b) a rocket? (c) a person walking?

Donald Albin

Numerade Educator

03:27

Problem 16

Suppose a large and spirited Freshman team is beating the Sophomores in a tug-of-war contest. The center of the rope being tugged is gradually accelerating toward the Freshman team. State the relationship between the strengths of these two forces: First, the force the Freshmen exert on the Sophomores; and second, the force the Sophomores exert on the Freshmen.

Donald Albin

Numerade Educator

02:25

Problem 17

If you push on a heavy box that is at rest, you must exert some force to start its motion. However, once the box is sliding, you can apply a smaller force to maintain that motion. Why?

Prabhu Ramji

Numerade Educator

01:42

Problem 18

A weight lifter stands on a bathroom scale. He pumps a barbell up and down. What happens to the reading on the scale as this is done? Suppose he is strong enough to actually throw the barbell upward. How does the reading on the scale vary now?

Prabhu Ramji

Numerade Educator

00:55

Problem 19

As a rocket is fired from a launching pad, its speed and acceleration increase with time as its engines continue to operate. Explain why this occurs even though the force of the engines exerted on the rocket remains constant.

Bettina Hanlon

Numerade Educator

00:51

Problem 20

In the motion picture It Happened One Night (Columbia Pictures, 1934), Clark Gable is standing inside a stationary bus in front of Claudette Colbert, who is seated. The bus suddenly starts moving forward, and Clark falls into Claudette's lap. Why did this happen?

Donald Albin

Numerade Educator