Question 1

A 100-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 25°.What is the coefficient of static friction between box and ramp?

Accepted Answer

A)  0.15 
B)  0.27 
C)  0.47 
D)  0.95

Question 2

A boxcar of mass 200 tons at rest becomes uncoupled on a 1.5° grade.If the track is considered to be frictionless,what speed does the boxcar have after 10 seconds?

Accepted Answer

A)  0.37 m/s 
B)  0.59 m/s 
C)  2.6 m/s 
D)  4.3 m/s

Question 3

A helicopter is traveling at 54 m/s at a constant altitude of 100 m over a level field.If a wheel falls off the helicopter,with what speed will it hit the ground? Note: g = 9.8 m/s2 and air resistance is negligible.

Accepted Answer

A)  40 m/s 
B)  50 m/s 
C)  60 m/s 
D)  70 m/s

Question 4

A 25-g traffic light hangs midway on a cable between two poles 40 meters apart.If the sag in the cable is 0.40 meters,what is the tension in each side of the cable?

Accepted Answer

A)  12,200 N 
B)  9800 N 
C)  4900 N 
D)  6100 N

Question 5

A baseball thrown from the outfield is released from shoulder height at an initial velocity of 39.2 m/s at an initial angle of 30.0° with respect to the horizontal.What is the maximum vertical displacement that the ball reaches during its trajectory?

Accepted Answer

A)  11.0 m 
B)  19.6 m 
C)  22.1 m 
D)  44.1 m

Question 6

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 30.0° with the vertical.In such a condition of static equilibrium what is the tension in the rope?

Accepted Answer

A)  924 N 
B)  404 N 
C)  808 N 
D)  233 N

Question 7

A 4000-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 T2.

Accepted Answer

A)  4000 N 
B)  6650 N 
C)  8310 N 
D)  3340 N

Question 8

A ball is rolled horizontally off a table with an initial speed of 0.18 m/s.A stopwatch measures the ball's trajectory time from table to the floor to be 0.30 s.How far away from the table does the ball land? Note: g = 9.8 m/s2 and air resistance is negligible.

Accepted Answer

A)  0.054 m 
B)  0.072 m 
C)  1.2 m 
D)  1.9 m

Question 9

A stone is thrown with an initial speed of 15 m/s at an angle of 53° above the horizontal from the top of a 40-m building.If g = 9.8 m/s2 and air resistance is negligible,what is the magnitude of the horizontal displacement of the rock?

Accepted Answer

A)  30 m 
B)  39 m 
C)  66 m 
D)  90 m

Question 10

Two ropes are attached to a 40-kg object.The first rope applies a force of 50 N and the second,40 N.If the two ropes are perpendicular to each other,what is the resultant magnitude of the acceleration of the object?

Accepted Answer

A)  1.2 m/s2 
B)  1.6 m/s2 
C)  25 m/s2 
D)  47 m/s2

Question 11

A baseball thrown from the outfield is released from shoulder height at an initial velocity of 39.2 m/s at an initial angle of 30.0° with respect to the horizontal.If it is in its trajectory for a total of 4.00 s before being caught by the third baseman at an equal shoulder-height level,what is the ball's net vertical displacement during its 4.00-s trajectory?

Accepted Answer

A)  11.0 m 
B)  9.80 m 
C)  22.1 m 
D)  zero

Question 12

A baseball leaves the bat with a speed of 44.0 m/s and an angle of 30.0° above the horizontal.A 4.0-m high fence is located at a horizontal distance of 132 m from the point where the ball is struck.Assuming the ball leaves the bat 1.0 m above ground level,by how much does the ball clear the fence?

Accepted Answer

A)  18.9 m 
B)  14.4 m 
C)  9.8 m 
D)  5.4 m

Question 13

A stone is thrown at an angle of 30° above the horizontal from the top edge of a cliff with an initial speed of 14 m/s.A stop watch measures the stone's trajectory time from top of cliff to bottom to be 7.1 s.What is the height of the cliff? Note: g = 9.8 m/s2 and air resistance is negligible.

Accepted Answer

A)  58 m 
B)  114 m 
C)  120 m 
D)  197 m

Question 14

A track star in the broad jump goes into the jump at 10 m/s and launches himself at 20° above the horizontal.How long is he in the air before returning to Earth? Note: g = 9.8 m/s2.

Accepted Answer

A)  0.35 s 
B)  0.42 s 
C)  0.70 s 
D)  0.89 s

Question 15

A ball is launched from ground level at 30 m/s at an angle of 25° above the horizontal.How far does it go before it is at ground level again?

Accepted Answer

A)  14 m 
B)  70 m 
C)  43 m 
D)  86 m

Question 16

A 250-kg crate is placed on an adjustable inclined plane.If the crate slides down the incline with an acceleration of 0.25 m/s2 when the incline angle is 25°,then what should the incline angle be for the crate to slide down the plane at constant speed? Note: g = 9.8 m/s2.

Accepted Answer

A)  12° 
B)  21° 
C)  24° 
D)  29°

Question 17

A 200-N crate rests on a ramp;the maximum angle just before it slips is 21° with the horizontal.What is the coefficient of static friction between crate and ramp surfaces?

Accepted Answer

A)  0.11 
B)  0.21 
C)  0.38 
D)  0.47

Question 18

A jet airliner moving at 600 mph due east moves into a region where the wind is blowing at 120 mph in a direction 30.0° north of east.What is the new speed and direction of the aircraft?

Accepted Answer

A)  706 mph,5.67° N of E 
B)  620 mph,5.67° N of E 
C)  706 mph,4.87° N of E 
D)  588 mph,4.87° N of E

Question 19

A boat moves at 11.0 m/s relative to the water.If the boat is in a river where the current is 2.00 m/s,how long does it take the boat to make a complete round trip of 1000 m upstream followed by a 1000 m trip downstream?

Accepted Answer

A)  188 s 
B)  205 s 
C)  208 s 
D)  222 s

Question 20

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?

Accepted Answer

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

Exam 4: The Laws of Motion: Part A

A 100-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 25°.What is the coefficient of static friction between box and ramp?

A boxcar of mass 200 tons at rest becomes uncoupled on a 1.5° grade.If the track is considered to be frictionless,what speed does the boxcar have after 10 seconds?

A helicopter is traveling at 54 m/s at a constant altitude of 100 m over a level field.If a wheel falls off the helicopter,with what speed will it hit the ground? Note: g = 9.8 m/s² and air resistance is negligible.

A 25-g traffic light hangs midway on a cable between two poles 40 meters apart.If the sag in the cable is 0.40 meters,what is the tension in each side of the cable?

A baseball thrown from the outfield is released from shoulder height at an initial velocity of 39.2 m/s at an initial angle of 30.0° with respect to the horizontal.What is the maximum vertical displacement that the ball reaches during its trajectory?

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 30.0° with the vertical.In such a condition of static equilibrium what is the tension in the rope?

A 4000-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 ball is rolled horizontally off a table with an initial speed of 0.18 m/s.A stopwatch measures the ball's trajectory time from table to the floor to be 0.30 s.How far away from the table does the ball land? Note: g = 9.8 m/s² and air resistance is negligible.

A stone is thrown with an initial speed of 15 m/s at an angle of 53° above the horizontal from the top of a 40-m building.If g = 9.8 m/s² and air resistance is negligible,what is the magnitude of the horizontal displacement of the rock?