Deck 4: Newtons Laws of Motion

Question 1

Rita accelerates a 0.50-kg ball from rest to 8.0 m/s during the 0.14 s in which her foot is in contact with the ball.What average force does she apply to the ball during the kick?

A)110 N
B)22 N
C)29 N
D)56 N
E)2.2 N

Answer 1

29 N

Question 2

Which of the following expresses a principle,which was initially stated by Galileo and was later incorporated into Newton's laws of motion?

A)An object's acceleration is inversely proportional to its mass.
B)For every action there is an equal but opposite reaction.
C)The natural condition for a moving object is to remain in motion.
D)The natural condition for a moving object is to come to rest.

Answer 2

The natural condition for a moving object is to remain in motion.

Question 3

An astronaut applies a force of 450 N to an asteroid,and it accelerates at 7.0 m/s².What is the asteroid's mass?

A)64 kg
B)450 kg
C)460 kg
D)3 200 kg
E)0.016 kg

Answer 3

64 kg

Question 4

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

Question 5

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

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 6

Two ropes are attached to a 50-kg object.The first rope applies a force of 35 N and the second,55 N.If the two ropes are perpendicular to each other,what is the resultant acceleration of the object?

A)1.3 m/s²
B)35 m/s²
C)1.8 m/s²
D)65 m/s²
E)0.77 m/s²

Question 7

Two forces act on a 8.50-kg object.One of the forces is 14.0 N.If the object accelerates at 3.50 m/s²,what is the greatest possible magnitude of the other force?

A)1.0 N
B)15.8 N
C)43.8 N
D)26.3 N
E)73.5 N

Question 8

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?

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 9

A cart of weight 15.0 N is accelerated across a level surface at 0.15 m/s².What net force acts on the wagon? (g = 9.8 m/s²)

A)22 N
B)0.23 N
C)2.3 N
D)10 N
E)100 N

Question 10

If we know that a nonzero net force is acting on an object,which of the following must we assume regarding the object's condition? The object is:

A)at rest.
B)moving with a constant velocity.
C)being accelerated.
D)losing mass.

Question 11

A shot-putter moves his arm and the 6.00-kg shot through a distance of 1.25 m,giving the shot a velocity of 8.20 m/s from rest.Find the average force exerted on the shot during this time.

A)323 N
B)161 N
C)118 N
D)12.7 N
E)252 N

Question 12

What condition must apply to a system's state of motion for it to be regarded as an inertial frame of reference?

A)in decreasing velocity
B)in constant velocity
C)in constant acceleration
D)in increasing acceleration

Question 13

An automobile of mass 2 500 kg moving at 50.0 m/s is braked suddenly with a constant braking force of 8 500 N.How far does the car travel before stopping?

A)7.35 m
B)368 m
C)184 m
D)551 m
E)19.2 m

Question 14

A 3 000-kg sailboat experiences an eastward force of 4 500 N by the ocean tide and a wind force against its sails with magnitude of 5 800 N directed toward the northwest (45° N of W).What is the magnitude of the resultant acceleration?

A)1.4 m/s²
B)3.2 m/s²
C)2.4 m/s²
D)3.4 m/s²
E)1.3 m/s²

Question 15

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

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

Question 16

The acceleration due to gravity on the Moon's surface is one-sixth that on Earth.What net force would be required to accelerate a 25.0-kg object at 5.80 m/s² on the Moon?

A)4.31 N
B)24.2 N
C)8.7 N
D)145 N
E)25.9 N

Question 17

A 3.0-kg bowling ball experiences a net force of 8.0 N.What will be its acceleration?

A)24 m/s²
B)3.0 m/s²
C)8.0 m/s²
D)2.7 m/s²
E)0.38 m/s²

Question 18

A 60.0-kg man jumps 1.70 m down onto a concrete walkway.His downward motion stops in 0.025 seconds.If he forgets to bend his knees,what force is transmitted to his leg bones?

A)13 900 N
B)346 N
C)8 000 N
D)1 790 N

Question 19

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

Question 20

A 2 000-kg sailboat experiences an eastward force of 4 500 N by the ocean tide and a wind force against its sails with magnitude of 1 500 N directed toward the northwest (45° N of W).What is the direction of the resultant acceleration?

A)27° N of W
B)58° N of W
C)27° N of E
D)17° N of W
E)17° N of E

Question 21

A thrown stone hits a window,but doesn't break it.Instead it reverses direction and ends up on the ground below the window.In this case,we know:

A)the force of the stone on the glass > the force of the glass on the stone.
B)the force of the stone on the glass = the force of the glass on the stone.
C)the force of the stone on the glass < the force of the glass on the stone.
D)the stone didn't slow down as it broke the glass.

Question 22

A 16-kg mass is placed on a 25° incline and friction keeps it from sliding.The coefficient of static friction in this case is 0.574 and the coefficient of sliding friction is 0.519.The mass is given a shove causing it to slide down the incline.Taking down the incline as positive,what is the acceleration of the mass while it is sliding?

A)0.47 m/s²
B)-0.47 m/s²
C)-0.96 m/s²
D)0.96 m/s²
E)​14.50 m/s²

Question 23

A 150-kg crate is placed on an adjustable inclined plane.If the crate slides down the incline with an acceleration of 0.70 m/s² when the incline angle is 20°,then what should the incline angle be for the crate to slide down the plane at constant speed? (g = 9.8 m/s²)

A)21°
B)16°
C)11°
D)26°
E)​6°

Question 24

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?

A)0.89
B)0.88
C)2.00
D)1.19
E)​0.84

Question 25

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?

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

Question 26

A worker pulls a 350-N packing crate at constant velocity across a rough floor by exerting a force F = 200.0 N at an angle of 30.0° above the horizontal.What is the coefficient of kinetic friction of the floor?

A)0.793
B)0.693
C)​0.593
D)​1.386
E)​0.400

Question 27

Doug hits a hockey puck,giving it an initial velocity of 6.0 m/s.If the coefficient of kinetic friction between ice and puck is 0.20,how far will the puck slide before stopping?

A)14 m
B)19 m
C)9 m
D)11 m
E)​24 m

Question 28

A block is launched up an incline plane.After going up the plane,it slides back down to its starting position.The coefficient of friction between the block and the plane is 0.3.The time for the trip up the plane:

A)is the same as the time for the trip down.
B)is more than the time for the trip down.
C)is less than the time for the trip down.
D)cannot be found without knowing the angle of inclination.

Question 29

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?

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

Question 30

In the terminology a 500-N block,the 500-N refers to the block's:

A)mass.
B)force.
C)weight.
D)None of the above.

Question 31

A 150-kg crate is placed on an adjustable inclined plane.As one end of the incline is raised,the crate begins to move downward.If the crate slides down the plane with an acceleration of 0.20 m/s² when the incline angle is 18°,what is the coefficient of kinetic friction between ramp and crate? (g = 9.8 m/s²)

A)0.40
B)0.50
C)0.30
D)0.20
E)2.8

Question 32

Jamal pulls a 250-N sled up a 29.0° slope at constant speed by a force of 200 N.Near the top of the hill he releases the sled.With what acceleration does the sled go down the hill?

A)7.84 m/s²
B)9.30 m/s²
C)3.32 m/s²
D)1.66 m/s²
E)​2.66 m/s²

Question 33

The statement by Newton that "for every action there is an opposite but equal reaction" is regarded as which of his laws of motion?

A)first
B)second
C)third
D)fourth

Question 34

A block of mass 4.0 kg rests on a horizontal surface where the coefficient of kinetic friction between the two is 0.20.A string attached to the block is pulled horizontally,resulting in a 3.0-m/s² acceleration by the block.Find the tension in the string.(g = 9.80 m/s²)

A)12 N
B)7.8 N
C)20 N
D)4.2 N

Question 35

A horizontal force of 675 N is needed to overcome the force of static friction between a level floor and a 300-kg crate.What is the acceleration of the crate if the 675-N force is maintained after the crate begins to move and the coefficient of kinetic friction is 0.15?

A)0.78 m/s²
B)3.7 m/s²
C)3.3 m/s²
D)1.5 m/s²
E)1.8 m/s²

Question 36

The net force on an object is in the positive x-direction.Consider the following statements.
(I)The object can be moving in the negative x-direction.
(II)The object can be speeding up.
(III)The object can be slowing down.
(IV)The object can be moving in the positive y-direction.
Which of the statements are true?

A)(I)and (II)
B)(II)and (III)
C)(III)and (IV)
D)Choose this answer if all the statements are true.

Question 37

A physics student is riding on a train traveling north.Having read about inertia,the student performs an experiment with a golf ball.He reaches over the aisle and drops the ball from rest.Instead of hitting the floor directly below the student's hand,it hits to the north,i.e. ,forward of that position.Which of the following might be the cause for this to happen?

A)The train is moving at constant velocity.
B)The train is speeding up.
C)The train is slowing down.
D)Whatever the cause,it cannot be any of the answers given.

Question 38

A 12.0-kg mass is placed on a 29.0° incline and friction keeps it from sliding.The coefficient of static friction in this case is 0.660,and the coefficient of sliding friction is 0.546.The mass is given a shove causing it to slide down the incline.What is the frictional force while the mass is sliding?

A)57.0 N
B)102.9 N
C)56.2 N
D)67.9 N
E)​10.5 N

Question 39

A man pulls a sled at a constant velocity across a horizontal snow surface.If a force of 85 N is being applied to the sled rope at an angle of 56° to the ground,what is the force of friction between sled and snow?

A)85 N
B)70 N
C)48 N
D)5 N
E)​43 N

Question 40

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?

A)0.21
B)0.41
C)0.11
D)1.55
E)​2.95

Question 41

As a car goes up a hill,there is a force of friction between the road and the tires rolling on the road.The maximum force of friction is equal to:

A)the weight of the car times the coefficient of kinetic friction.
B)the normal force of the road times the coefficient of kinetic friction.
C)the normal force of the road times the coefficient of static friction.
D)zero.

Question 42

A block is launched up an incline plane.After going up the plane,it slides back down to its starting position.The coefficient of friction between the block and the plane is 0.3.The speed of the block when it reaches the starting position on the trip down:

A)is the same as the launching speed.
B)is less than the launching speed.
C)is more than the launching speed.
D)cannot be compared to the launch speed with the information given.

Question 43

A horizontal force of 850 N is needed to overcome the force of static friction between a level floor and a 350-kg crate.If g = 9.8 m/s²,what is the coefficient of static friction?

A)24.8
B)2.48
C)4.04
D)0.248
E)2.43

Question 44

Hector drives a pickup truck horizontally at 9.00 m/s.He is transporting a crate of delicate lead crystal.If the coefficient of static friction between the crate and the truck bed is 0.740,what is the minimum stopping distance for the truck so the crate will not slide?

A)5.58 m
B)6.66 m
C)81.0 m
D)15.6 m
E)2.79 m

Question 45

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.

A)μ_B > μ_A
B)μ_A > μ_B
C)μ_B = 2 μ_A
D)μ_A = 2 μ_B

Question 46

A 400-N crate rests on a ramp;the maximum angle just before it slips is 15.0° with the horizontal.What is the coefficient of static friction between crate and ramp surfaces?

A)3.7
B)0.47
C)2.1
D)0.27
E)0.40

Question 47

A sled is on a horizontal surface and a rope with tension T is pulling on it at an angle θ above the horizontal.The sled had mass M and does not move due to the frictional force.In this case the coefficient of friction is μ​_s.In terms of the variables given and g,what is the magnitude of the frictional force in this case?

A)μ​_sMg
B)Tcosθ
C)Tsinθ
D)μ​_sMgcosθ

Question 48

As a car moves forward on a level road at constant velocity,the net force acting on the tires is:

A)greater than the normal force times the coefficient of static friction.
B)equal to the normal force times the coefficient of static friction.
C)the normal force times the coefficient of kinetic friction.
D)zero.

Question 49

A 200-kg box is placed on a ramp.As one end of the ramp is raised,the box begins to move downward just as the angle of inclination reaches 18.0°.What is the coefficient of static friction between box and ramp?

A)0.42
B)0.32
C)3.1
D)0.27
E)62

Question 50

A box is to be moved across a level surface.A force of magnitude 200 N may be applied at an angle of 30° below the horizontal to push the box or at an angle of 30° above the horizontal to pull the box,either application sufficient to overcome friction and move the box.Which application will cause the box to have the greater acceleration?

A)the one below the horizontal
B)the one above the horizontal
C)both give equal acceleration
D)more information is needed

Question 51

​What forces are included in a free-body diagram for an object?

A)​The forces acting on the object and the forces the object exerts on any other objects it is in contact with.
B)​The forces acting on the object and the forces the object exerts on all other objects in the system.
C)​Only the forces acting on the object.
D)​Only forces internal to the object.

Question 52

A 500-N block,on a 30.0° incline,is being held motionless by friction.The coefficient of static friction between the block and the plane is 0.63.The force due to friction is:

A)0 N.
B)433 N.
C)250 N.
D)500 N.
E)354 N.

Question 53

A crate of weight w is being pushed across a horizontal surface by a force directed at an angle of 20° below the horizontal.What is the magnitude of the normal force on the crate?

A)It is less than w.
B)It equals w.
C)It is more than w.
D)None of the above since the coefficient of kinetic friction is not given.

Question 54

A 7.00-kg mass is placed on a 28.0° incline and friction keeps it from sliding.The coefficient of static friction in this case is 0.574,and the coefficient of sliding friction is 0.528.What is the frictional force in this situation?

A)32.2 N
B)60.6 N
C)32.0 N
D)34.8 N
E)3.29 N

Question 55

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

Question 56

​The figure shows a block on an inclined plane.
What is the expression for the normal force acting on the block?

A)​Mg
B)​Mgcosθ
C)​Mgsinθ
D)​Mgtanθ

Question 57

The maximum possible value for the coefficient of static friction is:

A)0.50.
B)1.00.
C)a value up to but not quite 1.00.
D)greater than 1.00.

Question 58

A box of mass m is placed on an incline with angle of inclination θ.The box does not slide.The magnitude of the frictional force in this case is:

A)μ_s mg sin θ.
B)mg cos θ.
C)mg sin θ.
D)not given.

Question 59

​Which is the correct expression for the force of static friction,where n is the normal force?

A)​
B)​​
C)
D)

Question 60

The coefficient of static friction between the tires of a car and the street is μ_s = 0.70.Of the following,what is the steepest inclination angle of a street on which a car can be parked (with wheels locked)without slipping?

A)30°
B)40°
C)35°
D)45°
E)​32°

Question 61

A sled weighs 325 N.It is held in place on a frictionless 30.0° slope by a rope attached to a stake at the top;the rope is parallel to the slope.Find the tension in the rope.

A)281 N
B)650 N
C)375 N
D)163 N
E)188 N

Question 62

A girl is using a rope to pull a box that weighs 300 N across a level surface with constant velocity.The rope makes an angle of 30° above the horizontal,and the tension in the rope is 100 N.What is the normal force of the floor on the box?

A)350 N
B)200 N
C)400 N
D)250 N
E)213 N

Question 63

A trapeze artist,with swing,weighs 700 N;he is being held to one side by his partner so that the swing ropes make an angle of 40.0° with the vertical.In such a condition of static equilibrium,what is the tension in the rope?

A)9.1E+2 N
B)5.4E+2 N
C)700 N
D)1.4E+3 N
E)9.6E+2 N

Question 64

Two blocks of masses 20 kg and 9.0 kg are connected together by a light string and rest on a frictionless level surface.Attached to the 9.0-kg mass is another light string,which a person uses to pull both blocks horizontally.If the two-block system accelerates at 0.80 m/s²,what is the tension in the second string attached to the 9.0-kg mass?

A)23 N
B)14 N
C)16 N
D)7.2 N
E)25 N

Question 65

A 650-N tightrope walker stands at the center of the rope such that each half of the rope makes an angle of 10.0° with the horizontal.What is the tension in the rope?

A)1 870 N
B)660 N
C)3 740 N
D)226 N
E)1 840 N

Question 66

A box slides up an incline with an angle of elevation θ.When the box reaches its maximum distance up the incline it stops and does not slide down the incline due to friction.What is the minimum value of the coefficient of static friction for this to occur?

A)μ_s = tanθ
B)μ_s = sinθ
C)μ_s = cosθ
D)μ_s = 1

Question 67

Two blocks,joined by a string,have masses of 3.0 and 4.0 kg.They rest on a frictionless horizontal surface.A second string,attached only to the 4.0-kg block,has horizontal force = 40 N applied to it.Both blocks accelerate.Find the tension in the string between the blocks.

A)23 N
B)5.7 N
C)17 N
D)93 N
E)120 N

Question 68

An elevator weighing 20 000 N is supported by a steel cable.What is the tension in the cable when the elevator is being accelerated upward at a rate of 3.00 m/s²? (g = 9.80 m/s²)

A)6.1E+3 N
B)2.0E+4 N
C)6.0E+4 N
D)2.6E+4 N
E)6.7E+3 N

Question 69

Find the tension in an elevator cable if the 1 500-kg elevator is descending with an acceleration of 2.8 m/s²,downward.

A)1.9E+4 N
B)1.1E+4 N
C)4.2E+3 N
D)2.7E+1 N
E)2.1E+2 N

Question 70

A 4 500-N weight is suspended in equilibrium by two cables.Cable 1 applies a horizontal force to the right of the object and has a tension,T₁.Cable 2 applies a force upward and to the left at an angle of 37.0° to the negative x-axis and has a tension,T₂.Find T_2.

A)6.0E+3 N
B)2.7E+3 N
C)7.5E+3 N
D)5.6E+3 N
E)3.6E+3 N

Question 71

It is late and Carlos is sliding down a rope from his third-floor window to meet his friend Juan.As he slides down the rope faster and faster,he becomes frightened and grabs harder on the rope,increasing the tension in the rope.As soon as the upward tension in the rope becomes equal to his weight:

A)Carlos will stop.
B)Carlos will slow down.
C)Carlos will continue down at a constant velocity.
D)the rope must break.

Question 72

A 5 500-N weight is held suspended in equilibrium by two cables.Cable 1 applies a horizontal force to the right of the object and has a tension,T₁.Cable 2 applies a force upward and to the left at an angle of 40.0° to the negative x-axis and has a tension,T₂.What is the tension,T₁?

A)4.6E+3 N
B)6.6E+3 N
C)4.2E+3 N
D)8.6E+3 N
E)1.1E+4 N

Question 73

A 20.0-kg traffic light hangs midway on a cable between two poles 30.0 meters apart.If the sag in the cable is 0.40 meters,what is the tension in each side of the cable?

A)9.8E+1 N
B)9.8E+3 N
C)3.7E+3 N
D)3.8E+2 N
E)2.0E+4 N

Question 74

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)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 75

As I slide a box at constant speed up a frictionless slope,pulling parallel to the slope,the tension in the rope will be:

A)greater than the tension would be if the box were stationary.
B)greater than the weight of the box.
C)equal to the weight of the box.
D)less than the weight of the box.

Question 76

Two blocks of masses 30.0 kg and 8.0 kg are connected together by a light string and rest on a frictionless level surface.Attached to the 8.0-kg mass is another light string,which a person uses to pull both blocks horizontally.If the two-block system accelerates at 0.60 m/s² what is the tension in the connecting string between the blocks?

A)23 N
B)37 N
C)18 N
D)4.8 N
E)50 N

Question 77

A 500-N tightrope walker stands at the center of the rope.If the rope can withstand a tension of 1 800 N without breaking,what is the minimum angle the rope can make with the horizontal?

A)82°
B)8.0°
C)16°
D)0.40°
E)7.2°

Question 78

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:

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 79

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

Question 80

A 14-kg block rests on a level frictionless surface and is attached by a light string to a 5.0-kg hanging mass where the string passes over a massless frictionless pulley.If g = 9.8 m/s²,what is the tension in the connecting string?

A)2.6 N
B)21 N
C)49 N
D)36 N
E)190 N