Question 1

Its more difficult to start moving a heavy carton from rest than it is to keep pushing it with constant velocity, because

Accepted Answer

A) The normal force is greater when the carton is at rest. 
B)    <
  . 
C) Initially, the normal force is not perpendicular to the applied force. 
D)    <
  . 
E)    =
  . 
A) The normal force is greater when the carton is at rest. 
B)    <
  . 
C) Initially, the normal force is not perpendicular to the applied force. 
D)    <
  . 
E)    =
  .

Question 2

A car travels around 200 m radius flat curve at 40 m/s at constant speed. What is the minimum static coefficient of friction which allows it to travel at this speed without sliding?

Accepted Answer

A) 1.23 
B) 0.815 
C) 0.736 
D) 0.952 
E) 0.662 
A) 1.23 
B) 0.815 
C) 0.736 
D) 0.952 
E) 0.662

Question 3

Nonuniform circular motion occurs when the net force on an object is exerted toward the center of the circular path the object is following.

Accepted Answer

A) True 
 B)False

Question 4

Is it possible for an object moving with a constant speed to accelerate? Explain.

Accepted Answer

Yes, although the sp

Question 5

A 55-kg box rests on a horizontal surface. The coefficient of static friction between the box and the surface is 0.30. A 140-N force is applied to the box. What is the frictional force on the box?

Accepted Answer

The answer of A 55-kg box rests on a horizontal...

Question 6

FIGURE 5-5  
-A 50.0-kg block is being pulled up a 13.0° slope by a force of 250 N which is parallel to the slope. The coefficient of kinetic friction between the block and the slope is 0.200. What is the acceleration of the block?

Accepted Answer

A) 0.528 m/s2 
B) 0.158 m/s2 
C) 0.833 m/s2 
D) 0.983 m/s2 
E) 0.260 m/s2 
A) 0.528 m/s2 
B) 0.158 m/s2 
C) 0.833 m/s2 
D) 0.983 m/s2 
E) 0.260 m/s2

Question 7

When an object experiences uniform circular motion, the direction of the net force is

Accepted Answer

A) in the same direction as the motion of the object. 
B) in the opposite direction of the motion of the object. 
C) is directed toward the center of the circular path. 
D) is directed away from the center of the circular path. 
E) is dependent on the speed of the object. 
A) in the same direction as the motion of the object. 
B) in the opposite direction of the motion of the object. 
C) is directed toward the center of the circular path. 
D) is directed away from the center of the circular path. 
E) is dependent on the speed of the object.

Question 8

A 2-kg ball is moving with a constant speed of 5 m/s in a horizontal circle whose radius is 50 cm. What is the acceleration of the ball?

Accepted Answer

A) 0 m/s2 
B) 10 m/s2 
C) 20 m/s2 
D) 50 m/s2 
E) 500 m/s2 
A) 0 m/s2 
B) 10 m/s2 
C) 20 m/s2 
D) 50 m/s2 
E) 500 m/s2

Question 9

A body moving with constant speed cannot be accelerating.

Accepted Answer

A) True 
 B)False

Question 10

FIGURE 5-6  
-Two masses are connected by a string which goes over an ideal pulley as shown in Fig. 5-6. Block A has a mass of 3.00 kg and can slide along a rough plane inclined 30.0° to the horizontal. The coefficient of kinetic friction between block A and the plane is 0.400. Block B has a mass of 2.77 kg. What is the acceleration of the blocks?

Accepted Answer

A) 0.392 m/s2 
B) 1.96 m/s2 
C) 3.12 m/s2 
D) 5.35 m/s2 
E) 0 m/s2 
A) 0.392 m/s2 
B) 1.96 m/s2 
C) 3.12 m/s2 
D) 5.35 m/s2 
E) 0 m/s2

Question 11

When an object moves at constant speed on a circular path, which of the following is true?

Accepted Answer

A) A net force pointing along the direction of motion acts on the object. 
B) A net force pointing along the opposite direction of motion acts on the object. 
C) A net force pointing away from the center of the circle acts on the object. 
D) A net force pointing towards the center of the circle acts on the object. 
E) The net force acting on the object is zero. 
A) A net force pointing along the direction of motion acts on the object. 
B) A net force pointing along the opposite direction of motion acts on the object. 
C) A net force pointing away from the center of the circle acts on the object. 
D) A net force pointing towards the center of the circle acts on the object. 
E) The net force acting on the object is zero.

Question 12

A race car enters a flat 200-m radius curve at a speed of 20.0 m/s while increasing its speed at a constant 2.00 m/s2. If the coefficient of static friction is 0.700, what will the speed of the car be when the car begins to slide?

Accepted Answer

A) 36.2 m/s 
B) 24.3 m/s 
C) 37.1 m/s 
D) 28.7 m/s 
E) 31.5 m/s 
A) 36.2 m/s 
B) 24.3 m/s 
C) 37.1 m/s 
D) 28.7 m/s 
E) 31.5 m/s

Question 13

A car enters a 300-m radius flat curve on a rainy day when the coefficient of static friction between its tires and the road is 0.600. What is the maximum speed which the car can travel around the curve without sliding?

Accepted Answer

A) 29.6 m/s 
B) 33.1 m/s 
C) 24.8 m/s 
D) 42.0 m/s 
E) 37.9 m/s 
A) 29.6 m/s 
B) 33.1 m/s 
C) 24.8 m/s 
D) 42.0 m/s 
E) 37.9 m/s

Question 14

When a curve is properly banked a passenger in a car traveling on it at the designed speed does not feel a lateral force.

Accepted Answer

A) True 
 B)False

Question 15

Why does a cyclist tilt her bicycle on a curve?

Accepted Answer

In order to make the force of the seat n

Question 16

A 600-kg car is going around a curve with a radius of 120 m that is banked at an angle of 20° with a speed of 24.5 m/s. What is the minimum coefficient of static friction required for the car not to skid?

Accepted Answer

A) 0.12 
B) 0.24 
C) 0.36 
D) 0.48 
E) 0.60 
A) 0.12 
B) 0.24 
C) 0.36 
D) 0.48 
E) 0.60

Question 17

A child pulls a 3.00-kg sled across level ground at constant velocity with a light rope that makes an angle 34.0° above horizontal. The tension in the rope is 5.00 N. Assuming the acceleration of gravity is 9.81 m/s2, what is the coefficient of friction between the sled and the ground?

Accepted Answer

A) 0.156 
B) 0.188 
C) 0.0441 
D) 0.0851 
E) 0.103 
A) 0.156 
B) 0.188 
C) 0.0441 
D) 0.0851 
E) 0.103

Question 18

In problems involving a slope or inclined plane, the force due to gravity is always perpendicular to the slope or the plane.

Accepted Answer

A) True 
 B)False

Question 19

A car drives over a hilltop that has a radius of curvature 120 m at the top of the hill. At what speed would the car be traveling when it tires just barely lose contact with the road when the car is at the top of the hill?

Accepted Answer

A) 45.5 m/s 
B) 41.8 m/s 
C) 34.3 m/s 
D) 22.2 m/s 
E) 27.6 m/s 
A) 45.5 m/s 
B) 41.8 m/s 
C) 34.3 m/s 
D) 22.2 m/s 
E) 27.6 m/s

Question 20

A 1000-kg car is picking up speed as it goes around a horizontal curve whose radius is 100 m. The coefficient of static friction between the tires and the road is 0.350. At what speed will the car begin to skid sideways?

Accepted Answer

A) 9.25 m/s 
B) 23.6 m/s 
C) 34.3 m/s 
D) 35.0 m/s 
E) 18.5 m/s 
A) 9.25 m/s 
B) 23.6 m/s 
C) 34.3 m/s 
D) 35.0 m/s 
E) 18.5 m/s

Exam 5: Using Newtons Laws: Friction, Circular Motion, Drag Forces

Its more difficult to start moving a heavy carton from rest than it is to keep pushing it with constant velocity, because

A car travels around 200 m radius flat curve at 40 m/s at constant speed. What is the minimum static coefficient of friction which allows it to travel at this speed without sliding?

Nonuniform circular motion occurs when the net force on an object is exerted toward the center of the circular path the object is following.

Is it possible for an object moving with a constant speed to accelerate? Explain.

A 55-kg box rests on a horizontal surface. The coefficient of static friction between the box and the surface is 0.30. A 140-N force is applied to the box. What is the frictional force on the box?

FIGURE 5-5 -A 50.0-kg block is being pulled up a 13.0° slope by a force of 250 N which is parallel to the slope. The coefficient of kinetic friction between the block and the slope is 0.200. What is the acceleration of the block?

When an object experiences uniform circular motion, the direction of the net force is

A 2-kg ball is moving with a constant speed of 5 m/s in a horizontal circle whose radius is 50 cm. What is the acceleration of the ball?

A body moving with constant speed cannot be accelerating.

When an object moves at constant speed on a circular path, which of the following is true?

A race car enters a flat 200-m radius curve at a speed of 20.0 m/s while increasing its speed at a constant 2.00 m/s2. If the coefficient of static friction is 0.700, what will the speed of the car be when the car begins to slide?

A car enters a 300-m radius flat curve on a rainy day when the coefficient of static friction between its tires and the road is 0.600. What is the maximum speed which the car can travel around the curve without sliding?

When a curve is properly banked a passenger in a car traveling on it at the designed speed does not feel a lateral force.

Why does a cyclist tilt her bicycle on a curve?

A 600-kg car is going around a curve with a radius of 120 m that is banked at an angle of 20° with a speed of 24.5 m/s. What is the minimum coefficient of static friction required for the car not to skid?

A child pulls a 3.00-kg sled across level ground at constant velocity with a light rope that makes an angle 34.0° above horizontal. The tension in the rope is 5.00 N. Assuming the acceleration of gravity is 9.81 m/s2, what is the coefficient of friction between the sled and the ground?

In problems involving a slope or inclined plane, the force due to gravity is always perpendicular to the slope or the plane.

A car drives over a hilltop that has a radius of curvature 120 m at the top of the hill. At what speed would the car be traveling when it tires just barely lose contact with the road when the car is at the top of the hill?

A 1000-kg car is picking up speed as it goes around a horizontal curve whose radius is 100 m. The coefficient of static friction between the tires and the road is 0.350. At what speed will the car begin to skid sideways?

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A race car enters a flat 200-m radius curve at a speed of 20.0 m/s while increasing its speed at a constant 2.00 m/s². If the coefficient of static friction is 0.700, what will the speed of the car be when the car begins to slide?

A child pulls a 3.00-kg sled across level ground at constant velocity with a light rope that makes an angle 34.0° above horizontal. The tension in the rope is 5.00 N. Assuming the acceleration of gravity is 9.81 m/s², what is the coefficient of friction between the sled and the ground?