Question 1

Why does it hurt more to fall from a certain height to the ground than it does to fall from the same height into a swimming pool?

Accepted Answer

The answer of Why does it hurt more to fall...

Question 2

An astronaut weighs 99.0 N on the Moon, where the acceleration of gravity is 1.62 m/s2. How much does she weigh on Earth?

Accepted Answer

A)  16.2 N 
B)  61.0 N 
C)  99.0 N 
D)  600 N 
E)  440 N

Question 3

The acceleration of an object does not have to be in the same direction as the net force applied to it.

Accepted Answer

A) True 
 B)False

Question 4

A locomotive is pulling a number of identical wagons along a level track and accelerating. Friction is negligible. Starting from the last wagon, the ratio of the forces between adjacent wagons is

Accepted Answer

A)  1:2:3:4 . . . 
B)  1:2:4:8 . . . 
C)  1:3:5:7 . . . 
D)   . . . 
E)  1:1:1:1 . . .

Question 5

A 10.0-kg picture is held in place by two wires, one hanging at 50.0° to the left of the vertical and the other at 45.0° to the right of the vertical. What is the tension in the first wire?

Accepted Answer

A)  69.6 N 
B)  50.8 N 
C)  98.1 N 
D)  69.4 N 
E)  23.8 N

Question 6

A person is lowering a bucket into a well with a constant speed. The force exerted by the rope on the bucket is

Accepted Answer

A)  equal to the bucket's weight. 
B)  greater than the bucket's weight. 
C)  less than the bucket's weight, but not zero N. 
D)  zero N. 
E)  Cannot be determined without additional information.

Question 7

A fireman is sliding down a fire pole. As he speeds up, he tightens his grip on the pole, thus increasing the vertical frictional force that the pole exerts on the fireman. When this force equals the weight of the fireman, what happens?

Accepted Answer

A)  The fireman comes to a stop. 
B)  The fireman descends with slower and slower speed. 
C)  The fireman descends with a smaller acceleration. 
D)  The fireman continues to descend, but with constant speed. 
E)  Cannot be determined without additional information.

Question 8

Imagine that the metal head of a hammer is loose. In order to get the hammerhead tight again you should

Accepted Answer

A)  drop the hammer on its side from some given height. 
B)  drop the hammer with the handle end down. 
C)  drop the hammer with the head end down. 
D)  It makes no difference how you drop the hammer, the head will be tightened. 
E)  It makes no difference how you drop the hammer, the head will not be tightened.

Question 9

A locomotive is pulling three wagons along a level track with a force of 100,000 N. The wagon next to the locomotive has a mass of 80,000 kg, the next one, 50,000 kg, and the last one, 70,000 kg. Neglect friction. What is the force between the 50,000-kg and 70,000-kg wagons?

Accepted Answer

A)  35,000 N 
B)  40,000 N 
C)  50,000 N 
D)  60,000 N 
E)  65,000 N

Question 10

A 45.0-kg person steps on a scale in an elevator. The scale reads 460 N. What is the magnitude of the acceleration of the elevator?

Accepted Answer

A)  4.91 m/s2 
B)  9.81 m/s2 
C)  46.9 m/s2 
D)  0.206 m/s2 
E)  0.422 m/s2

Question 11

An object is being acted upon by three forces and moves with a constant velocity. One force is 60 N along the x-axis, the second is 75 N along a direction making a clockwise angle of 150° with the x-axis. What is the direction of the third force, measured clockwise from the x-axis?

Accepted Answer

A)  164° 
B)  146° 
C)  236° 
D)  255° 
E)  262°

Question 12

Two forces act on a 4.00-kg object in a manner that the object has an acceleration 3.00 m/s2 in a direction 20.0° north of east. The first force is 15.00 N in a direction 10.0° west of north. What is the second force?

Accepted Answer

A)  14.6 N in a direction 28.1° south of east 
B)  12.9 N in a direction 28.1° south of east 
C)  16.2 N in a direction 30.2° south of east 
D)  18.8 N in a direction 41.1° south of east 
E)  17.5 N in a direction 37.5° south of east

Question 13

Three boxes rest side-by-side on a smooth, horizontal floor. Their masses are 5.0 kg, 3.0 kg, and 2.0 kg, with the 3.0-kg mass in the center. A force of 50 N pushes on the 2.0-kg mass, which pushes against the other two masses. What is the contact force between the 3.0-kg mass and the 2.0-kg mass?

Accepted Answer

A)  0 N 
B)  10 N 
C)  25 N 
D)  40 N 
E)  50 N

Question 14

A 50.0-kg crate is being pulled along a horizontal, smooth surface. The pulling force is 10.0 N and is directed 20.0° above the horizontal. What is the acceleration of the crate?

Accepted Answer

A)  0.0684 m/s2 
B)  0.188 m/s2 
C)  0.200 m/s2 
D)  0.376 m/s2 
E)  0.0728 m/s2

Question 15

A ball is thrown up into the air. Ignore air resistance. When it is rising and reaches half of its maximum height, the net force acting on it is

Accepted Answer

A)  equal to its weight. 
B)  greater than its weight. 
C)  less than its weight, but not zero N. 
D)  zero N. 
E)  Cannot be determined without additional information.

Question 16

A 777 aircraft has a mass of 300,000 kg. At a certain instant during its landing, its speed is 27.0 m/s. If the braking force is 435,000 N, how much further does it travel along the runway before it comes to a stop?

Accepted Answer

A)  40.5 m 
B)  142 m 
C)  181 m 
D)  251 m 
E)  456 m

Question 17

A force is required for an object to move.

Accepted Answer

A) True 
 B)False

Question 18

A 30.0-kg object slides down a slope which is inclined 27.0° to the horizontal. What is the normal force on the object?

Accepted Answer

A)  133 N 
B)  171 N 
C)  262 N 
D)  387 N 
E)  398 N

Question 19

An object of mass m sits on a flat table. The Earth pulls on this object with force mg, which we will call the action force. What is the reaction force?

Accepted Answer

A)  The table pushing up on the object with force mg. 
B)  The object pushing down on the table with force mg. 
C)  The table pushing down on the floor with force mg. 
D)  The object pulling upward on the Earth with force mg. 
E)  The table pulling upward on the Earth with force mg.

Question 20

A block lies on a horizontal frictionless surface. A horizontal force of 100 N is applied to the block giving rise to an acceleration of 3 m/s². (a) Determine the mass of the block. (b) Calculate the distance the block will travel is the force is applied for 10 s. (c) Calculate the speed of the block after the force has been applied for 10 s.

Accepted Answer

The answer of A block lies on a horizontal frictionless...

Exam 5: Newtons Laws of Motion