Question 1

A 300-N sled is pulled up a 28° slope at a constant speed by a force of 250 N.What is the coefficient of kinetic friction between sled and slope?

Accepted Answer

A) 0.21 
B) 0.41 
C) 0.11 
D) 1.55 
E) ​2.95 
A) 0.21 
B) 0.41 
C) 0.11 
D) 1.55 
E) ​2.95 B

Question 2

Jack pulls a sled across a level field by exerting a force of 120.0 N at an angle of 30.0° with the ground.What are the parallel and perpendicular components,respectively,of this force with respect to the ground?

Accepted Answer

A) 208 N,120 N 
B) 120 N,208 N 
C) 104 N,60 N 
D) 60 N,104 N 
E) 69 N,208 N 
A) 208 N,120 N 
B) 120 N,208 N 
C) 104 N,60 N 
D) 60 N,104 N 
E) 69 N,208 N C

Question 3

A sled weighs 160 N.It is held in place on a frictionless 25.0° slope by a rope attached to a stake at the top;the rope is parallel to the slope.What is the normal force of the slope acting on the sled?

Accepted Answer

A) 145 N 
B) 67.6 N 
C) 177 N 
D) 379 N 
E) 74.6 N 
A) 145 N 
B) 67.6 N 
C) 177 N 
D) 379 N 
E) 74.6 N A

Question 4

A string is attached to the ceiling.At the bottom of the string a rope of the same length as the string is attached.In the rope-string system,which of the following is the position of greatest tension? Assume the rope has more mass per unit length than the string.

Accepted Answer

A) at the bottom of the rope 
B) at the top of the rope where it is attached to the string 
C) at the bottom of the string where it is attached to the rope 
D) at the top of the string 
A) at the bottom of the rope 
B) at the top of the rope where it is attached to the string 
C) at the bottom of the string where it is attached to the rope 
D) at the top of the string

Question 5

A baseball is moving in the air along the customary parabola.Ignoring air drag,where is the force on the baseball zero?

Accepted Answer

A) at the top of the parabola 
B) just when it has started upward 
C) where it is about to impact 
D) nowhere 
A) at the top of the parabola 
B) just when it has started upward 
C) where it is about to impact 
D) nowhere

Question 6

If we know an object is moving at constant velocity,we may assume:

Accepted Answer

A) the net force acting on the object is zero. 
B) there are no forces acting on the object. 
C) the object is accelerating. 
D) the object is losing mass. 
A) the net force acting on the object is zero. 
B) there are no forces acting on the object. 
C) the object is accelerating. 
D) the object is losing mass.

Question 7

As a 3.0-kg bucket is being lowered into a 14-m-deep well,starting from the top,the tension in the rope is 9.0 N.The acceleration of the bucket will be:

Accepted Answer

A) 6.8 m/s2 downward. 
B) 9 m/s2 downward. 
C) zero. 
D) 3.0 m/s2 upward. 
E) 6.8 m/s2 upward. 
A) 6.8 m/s2 downward. 
B) 9 m/s2 downward. 
C) zero. 
D) 3.0 m/s2 upward. 
E) 6.8 m/s2 upward.

Question 8

There are nine books in a stack,each with a weight of 6 N.The coefficient of friction between all the books is 0.3 as is the coefficient between the table and the bottom book.What horizontal push must I just exceed on the next to bottom book to start sliding the top eight books off the bottom one?

Accepted Answer

A) 1.80 N 
B) 14.4 N 
C) 48.0 N 
D) 16.2 N 
A) 1.80 N 
B) 14.4 N 
C) 48.0 N 
D) 16.2 N

Question 9

A 9.0-kg hanging weight is connected by a string over a pulley to a 5.0-kg block sliding on a flat table.If the coefficient of sliding friction is 0.19,find the tension in the string.
​  
​

Accepted Answer

A) 59.0 N 
B) 67.5 N 
C) 20.7 N 
D) 37.5 N 
A) 59.0 N 
B) 67.5 N 
C) 20.7 N 
D) 37.5 N

Question 10

A 6.0-kg object is falling downward with an acceleration of 3.27 m/s2.Of the following values,which is nearest to the drag force on the object?

Accepted Answer

A) 3.3 N 
B) 65 N 
C) 20 N 
D) 39 N 
A) 3.3 N 
B) 65 N 
C) 20 N 
D) 39 N

Question 11

Which of the following is an example of the type of force that acts at a distance?

Accepted Answer

A) gravitational 
B) magnetic 
C) electrical 
D) all of the above 
A) gravitational 
B) magnetic 
C) electrical 
D) all of the above

Question 12

A barefoot field-goal kicker imparts a speed of 30 m/s to a football at rest.If the football has a mass of 0.45 kg and time of contact with the football is 0.035 s,what is the force exerted on the foot?

Accepted Answer

A) 14 N 
B) 13 N 
C) 390 N 
D) 860 N 
E) 900 N 
A) 14 N 
B) 13 N 
C) 390 N 
D) 860 N 
E) 900 N

Question 13

A baseball batter hits an incoming 45.0-m/s fastball.The ball leaves the bat at 56.0 m/s after a ball-on-bat contact time of 0.040 s.What is the force exerted on the 0.25-kg baseball?

Accepted Answer

A) 631 N 
B) 68.8 N 
C) 350 N 
D) 16.2 N 
E) 281 N 
A) 631 N 
B) 68.8 N 
C) 350 N 
D) 16.2 N 
E) 281 N

Question 14

The acceleration due to gravity on the Moon's surface is one-sixth that on Earth.An astronaut's life support backpack weighs 250 lb on Earth.What does it weigh on the Moon?

Accepted Answer

A) 1 500 lb 
B) 250 lb 
C) 256 lb 
D) 41.7 lb 
E) 244 lb 
A) 1 500 lb 
B) 250 lb 
C) 256 lb 
D) 41.7 lb 
E) 244 lb

Question 15

Three identical 4.0-kg cubes are placed on a horizontal frictionless surface in contact with one another.The cubes are lined up from left to right and a force is applied to the left side of the left cube causing all three cubes to accelerate to the right at 4.0 m/s2.What is the magnitude of the force exerted on the right cube by the middle cube in this case?

Accepted Answer

A) 16 N 
B) 32 N 
C) 24 N 
D) 19 N 
E) none of the above 
A) 16 N 
B) 32 N 
C) 24 N 
D) 19 N 
E) none of the above

Question 16

A hockey puck moving at 7.00 m/s coasts to a halt in 80.0 m on a smooth ice surface.What is the coefficient of friction between the ice and the puck?

Accepted Answer

A) μ = 0.109 
B) μ = 0.031 
C) μ = 0.063 
D) μ = 0.094 
E) ​μ = 0.156 
A) μ = 0.109 
B) μ = 0.031 
C) μ = 0.063 
D) μ = 0.094 
E) ​μ = 0.156

Question 17

Two objects,A and B,are placed on an inclined plane that can be rotated to different angles of elevation.A starts to slide at twice the angle of elevation that B starts sliding.The respective coefficients for static friction for A and B are μA and μB.Choose the last answer that is correct.

Accepted Answer

A) μB > μA 
B) μA > μB 
C) μB = 2 μA 
D) μA = 2 μB 
A) μB > μA 
B) μA > μB 
C) μB = 2 μA 
D) μA = 2 μB

Question 18

The accelerating force of the wind on a small 300-kg sailboat is 780 N northeast.If the drag of the keel is 552 N acting west,what is the acceleration of the boat?

Accepted Answer

A) 4.4 m/s2 due east 
B) 1.8 m/s2 due north 
C) 2.6 m/s2 northeast 
D) 3.2 m/s2 north by northwest 
E) 0.23 m/s2 due east 
A) 4.4 m/s2 due east 
B) 1.8 m/s2 due north 
C) 2.6 m/s2 northeast 
D) 3.2 m/s2 north by northwest 
E) 0.23 m/s2 due east

Question 19

Dana uses a rope to pull a box that weighs 600 N across a level surface with constant velocity.The rope makes an angle of 40° above the horizontal and the tension in the rope is 400 N.What is the coefficient of friction?

Accepted Answer

A) 0.89 
B) 0.88 
C) 2.00 
D) 1.19 
E) ​0.84 
A) 0.89 
B) 0.88 
C) 2.00 
D) 1.19 
E) ​0.84

Question 20

Three forces,14.0 N,25.0 N,and 20.0 N,are acting on a 9.6-kg object.Which of the following forces could also be acting on the object if it is moving with constant velocity?

Accepted Answer

A) 1.0 N 
B) 17 N 
C) 30 N 
D) 5.0 N 
E) any of the above 
A) 1.0 N 
B) 17 N 
C) 30 N 
D) 5.0 N 
E) any of the above

Exam 4: Newtons Laws of Motion

A 300-N sled is pulled up a 28° slope at a constant speed by a force of 250 N.What is the coefficient of kinetic friction between sled and slope?

Jack pulls a sled across a level field by exerting a force of 120.0 N at an angle of 30.0° with the ground.What are the parallel and perpendicular components,respectively,of this force with respect to the ground?

A sled weighs 160 N.It is held in place on a frictionless 25.0° slope by a rope attached to a stake at the top;the rope is parallel to the slope.What is the normal force of the slope acting on the sled?

A string is attached to the ceiling.At the bottom of the string a rope of the same length as the string is attached.In the rope-string system,which of the following is the position of greatest tension? Assume the rope has more mass per unit length than the string.

A baseball is moving in the air along the customary parabola.Ignoring air drag,where is the force on the baseball zero?

If we know an object is moving at constant velocity,we may assume:

As a 3.0-kg bucket is being lowered into a 14-m-deep well,starting from the top,the tension in the rope is 9.0 N.The acceleration of the bucket will be:

There are nine books in a stack,each with a weight of 6 N.The coefficient of friction between all the books is 0.3 as is the coefficient between the table and the bottom book.What horizontal push must I just exceed on the next to bottom book to start sliding the top eight books off the bottom one?

A 9.0-kg hanging weight is connected by a string over a pulley to a 5.0-kg block sliding on a flat table.If the coefficient of sliding friction is 0.19,find the tension in the string. ​ ​

A 6.0-kg object is falling downward with an acceleration of 3.27 m/s2.Of the following values,which is nearest to the drag force on the object?

Which of the following is an example of the type of force that acts at a distance?

A barefoot field-goal kicker imparts a speed of 30 m/s to a football at rest.If the football has a mass of 0.45 kg and time of contact with the football is 0.035 s,what is the force exerted on the foot?

A baseball batter hits an incoming 45.0-m/s fastball.The ball leaves the bat at 56.0 m/s after a ball-on-bat contact time of 0.040 s.What is the force exerted on the 0.25-kg baseball?

The acceleration due to gravity on the Moon's surface is one-sixth that on Earth.An astronaut's life support backpack weighs 250 lb on Earth.What does it weigh on the Moon?

A hockey puck moving at 7.00 m/s coasts to a halt in 80.0 m on a smooth ice surface.What is the coefficient of friction between the ice and the puck?

Two objects,A and B,are placed on an inclined plane that can be rotated to different angles of elevation.A starts to slide at twice the angle of elevation that B starts sliding.The respective coefficients for static friction for A and B are μA and μB.Choose the last answer that is correct.

The accelerating force of the wind on a small 300-kg sailboat is 780 N northeast.If the drag of the keel is 552 N acting west,what is the acceleration of the boat?

Dana uses a rope to pull a box that weighs 600 N across a level surface with constant velocity.The rope makes an angle of 40° above the horizontal and the tension in the rope is 400 N.What is the coefficient of friction?

Three forces,14.0 N,25.0 N,and 20.0 N,are acting on a 9.6-kg object.Which of the following forces could also be acting on the object if it is moving with constant velocity?

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A 9.0-kg hanging weight is connected by a string over a pulley to a 5.0-kg block sliding on a flat table.If the coefficient of sliding friction is 0.19,find the tension in the string.

A 6.0-kg object is falling downward with an acceleration of 3.27 m/s².Of the following values,which is nearest to the drag force on the object?

Two objects,A and B,are placed on an inclined plane that can be rotated to different angles of elevation.A starts to slide at twice the angle of elevation that B starts sliding.The respective coefficients for static friction for A and B are μ_A and μ_B.Choose the last answer that is correct.