Question 1

A 15-kg block rests on a level,frictionless surface and is attached by a light string to a 10-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?

Accepted Answer

A)  65 N 
B)  17 N 
C)  59 N 
D)  37 N

Question 2

Jamal pulls a 150-N sled up a 28.0° slope at constant speed by a force of 120 N.Near the top of the hill he releases the sled.With what acceleration does the sled go down the hill?

Accepted Answer

A)  1.20 m/s2 
B)  1.36 m/s2 
C)  2.22 m/s2 
D)  2.67 m/s2

Question 3

The accelerating force of the wind on a small 250-kg sailboat is 707 N northeast.If the drag of the keel is 500 N acting west,what is the acceleration of the boat?

Accepted Answer

A)  1.5 m/s2 due east 
B)  2.5 m/s2 due north 
C)  3.0 m/s2 northeast 
D)  2.0 m/s2 due north

Question 4

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 0.10,find the tension in the string.

Accepted Answer

A)  19 N 
B)  24 N 
C)  35 N 
D)  38 N

Question 5

A fireman,40.0 m away from a burning building,directs a stream of water from a fire hose at an angle of 30.0° above the horizontal.If the initial speed of the stream is 40.0 m/s,at what height above the nozzle will the stream of water strike the building?

Accepted Answer

A)  9.60 m 
B)  16.6 m 
C)  18.7 m 
D)  22.4 m

Question 6

John throws a baseball from the outfield from shoulder height,at an initial velocity of 39.2 m/s at an initial angle of 30.0° with respect to the horizontal.The ball is in its trajectory for a total interval of 4.00 s before the third baseman catches it at an equal shoulder-height level.(Assume air resistance is negligible. )What is the ball's horizontal displacement?

Accepted Answer

A)  76.4 m 
B)  38.2 m 
C)  136 m 
D)  zero

Question 7

Plane A is flying at 600 mph in the northeast direction relative to the Earth.Plane B is flying at 500 mph in the north direction relative to the Earth.What is the speed of Plane B as observed from Plane A?

Accepted Answer

A)  900 mph 
B)  431 mph 
C)  357 mph 
D)  100 mph

Question 8

A 10-kg mass and a 6.0-kg mass are connected by a light string over a massless,frictionless pulley.If g = 9.8 m/s2,what is the acceleration of the system when released?

Accepted Answer

A)  2.5 m/s2 
B)  6.5 m/s2 
C)  7.8 m/s2 
D)  9.8 m/s2

Question 9

Plane A is flying at 600 mph in the northeast direction relative to the Earth.Plane B is flying at 500 mph in the north direction relative to the Earth.What is the direction of motion of Plane B as observed from Plane A?

Accepted Answer

A)  52.5° N of E 
B)  48.2° N of W 
C)  37.5° N of W 
D)  10.1° N of W

Question 10

Wiley Coyote has missed the elusive Road Runner once again.This time,he leaves the edge of the cliff at 40.0 m/s horizontal velocity.If the canyon is 100 m deep,how far from his starting point on the edge of the cliff does the coyote land?

Accepted Answer

A)  207 m 
B)  247 m 
C)  339 m 
D)  400 m

Question 11

A projectile is launched at an angle less than 30° and at speed v.Which will increase the projectile's range more,ignoring atmospheric drag?

Accepted Answer

A)  doubling the launch angle 
B)  increasing the speed of launch by 50% 
C)  reducing the mass of the projectile 
D)  launching on February 29th

Question 12

Two baseballs are released at the same time.One is dropped from rest and the other is given an initial horizontal velocity.Which of the following is not true? Ignore atmospheric drag.

Accepted Answer

A)  Both baseballs hit the ground at the same time. 
B)  Both have the same vertical component of velocity as they reach impact. 
C)  The horizontal component of velocity increases at a greater rate than the vertical component of velocity for both while they are both in the air. 
D)  The horizontally-released ball has a greater speed than the other ball for the whole trip.

Question 13

A 500-N tightrope walker stands at the center of the rope such that each half of the rope makes an angle of 15.0° with the horizontal.What is the tension in the rope?

Accepted Answer

A)  1440 N 
B)  970 N 
C)  480 N 
D)  2900 N

Question 14

A plane is moving due north,directly towards its destination.Its airspeed is 200 mph.A constant breeze is blowing from west to east at 42 mph.In which direction is the plane pointed?

Accepted Answer

A)  5.7° W of N 
B)  12° W of N 
C)  22° W of N 
D)  11° E of N

Question 15

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,then what is the magnitude of the vertical velocity component of the rock as it hits the ground?

Accepted Answer

A)  30 m/s 
B)  24 m/s 
C)  26 m/s 
D)  29 m/s

Question 16

A boat travels upstream and after one hour has gone 10 km.The boat next travels downstream and after one hour has gone 16 km.If the boat's speed relative to the water is constant,what is the speed of the current in the river?

Accepted Answer

A)  1 km/h 
B)  2 km/h 
C)  3 km/h 
D)  4 km/h

Question 17

A sled weighs 100 N.It is held in place on a frictionless 30° slope by a rope attached to a stake at the top;the rope is parallel to the slope.What is the normal force acting on the sled?

Accepted Answer

A)  94 N 
B)  87 N 
C)  50 N 
D)  34 N

Question 18

A trapeze artist,with swing,weighs 700 N;he is momentarily 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 horizontal force being applied by the partner?

Accepted Answer

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

Question 19

A river flows due east at 2.0 m/s.A boat crosses the 300 m-wide river by maintaining a constant velocity of 10 m/s due north relative to the water.If no correction is made for the current,how far downstream does the boat move by the time it reaches the far shore?

Accepted Answer

A)  6 m 
B)  30 m 
C)  60 m 
D)  90 m

Question 20

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.What is the height of the table? Note: g = 9.8 m/s2 and air resistance is negligible.

Accepted Answer

A)  0.11 m 
B)  0.22 m 
C)  0.33 m 
D)  0.44 m

Exam 4: The Laws of Motion: Part A

A 15-kg block rests on a level,frictionless surface and is attached by a light string to a 10-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?