Choose the best answer to each question and write the appropriate letter in the space provided.
1) Accelerations are produced by __________.
A) directly proportional.
3) The acceleration produced by a net force on an object is __________.
A) directly proportional to the magnitude
of the net force.
4) When an object reaches terminal velocity its acceleration is __________.
A) 9.8 m/s to power of (2). B) 4.9 m/s to power of (2). C) 0 m/s to power of (2).
A) the light person
6) A 10-kg brick and a 1-kg book are dropped in a vacuum. The force of gravity on the 10-kg brick is __________.
A) the same as the force on the 1-kg
7) Compared to its weight on earth, a 10-kg object on the moon will weigh __________.
8) Suppose the force of friction on a sliding object is 10 N. The force needed to maintain a constant velocity is __________.
A) more than 10 N.
9) An apple weighs 1 N. When held at rest above your head, the net force on the apple is __________.
A) 0 N.
10) An apple weighs 1 N. The net force on the apple when it is in free fall is __________.
A) 0 N.
A) 0.3 m/s to power of (2)
12) An object has a constant mass. A constant force on the object produces constant __________.
A) velocity. B) acceleration. C) both A and B D) none of the above
13) A force of 100 N accelerates a mass of 1 kg at the rate of 1 meter per second squared. The acceleration of a mass of 2 kg acted upon by a force of 2 N is __________.
A) half as much. B) twice as much. C) the same. D) none of the above
14) A push on a 1-kilogram brick accelerates the brick. Neglecting friction, to equally accelerate a 10-kilogram brick, one would have to push __________.
A) with just as much force.
15) A rock is thrown vertically into the air. At the very top of its trajectory the net force on it is __________.
A) less than its weight.
16) A block is dragged without acceleration in a straight-line path across a level surface by a force of 6 N. What is the frictional force between the block and the surface?
A) Less than 6 N
17) Suppose a particle is accelerated through space by a constant 10-N force. Suddenly the particle encounters a second force of 10-N in a direction opposite to that of the first force. The particle __________.
A) is brought to a rapid halt.
is defined as __________.
19) The unit of pressure is __________.
A) the newton.
20) Which of the following would exert the most pressure on the ground?
A) A woman standing in running shoes
21) A tennis ball and a solid steel ball the same size are dropped at the same time. Which ball has the greater force acting on it?
A) the tennis ball
tennis ball and a solid steel ball the same size are dropped at the
same time. In the absence of air resistance, which ball has the greater
23) The reason a tennis ball and a solid steel ball will accelerate at the same rate, in the absence of air resistance, is that __________.
A) the force acting on them is the same.
24) The terminal speed for a person parachuting (with the chute open) is about __________.
A) 1500 km/h. B) 150 km/h. C) 15 km/h. D) 0 km/h.
25) Aunt Minnie throws a rock downward, and air resistance is negligible. The acceleration of the rock compared to being dropped is __________.
A) more. B) the same. C) less.
26) As Bob falls from a high-flying stationary helicopter, his velocity increases and his acceleration __________.
27) If you pull horizontally on a crate with a force of 150 N and the crate doesn't move, the friction force must be 150 N. Now if you pull with 250 N so the crate slides at constant velocity, the friction force is __________.
A) more than 150 N but less than 250
28) When the angle of an incline with a block resting on it increases, the normal support force __________.
A) increases. B) decreases. C) stays the same.
29) A block is at rest on an incline. The force of friction necessary to prevent the block from sliding increases when the incline angle is __________.
30) Consider a ball rolling down the decreasing slope inside a semicircular bowl (the slope is steep at the top rim, gets less steep toward the bottom, and is zero (no slope) at the bottom). As the ball rolls from the rim downward toward the bottom, its rate of gaining speed __________.
31) A speeding truck slams it brakes and it skids to a stop. If the truck's total mass were doubled, its skidding distance would be __________.
A) half as far.
32) If the force acting on a cart doubles, what happens to the cart's acceleration?
A) It quadruples.
33) Suppose a cart is being moved by a force. If suddenly a load is dumped into the cart so that the cart's mass doubles, what happens to the cart's acceleration?
A) It quadruples.
34) A girl whose weight is 200 N hangs from a bar supported by two vertical strands of rope. What is the tension in each strand?
A) 400 N B) 300 N C) 200 N D) 100 N E) 0 N
35) A 10-N falling object encounters 4 N of air resistance. The magnitude of the net force on the object is __________.
A) 0 N.
36) A car has a mass of 1000 kg and accelerates at 2 meters per second per second. What is the magnitude of the force acting on the car?
A) 500 N.
37) A tow truck exerts a force of 3000 N on a car, accelerating it at 2 m/s/s. What is the mass of the car?
A) 500 kg
38) A 747 jumbo jet has a mass of 30000 kg. The thrust for each of four engines is 15000 N. What is the jet's acceleration when taking off?
A) 0.25 m/s to power of (2)
pull horizontally on a 50-kg crate with a force of 500 N, and the friction
force on the crate is 250 N. The acceleration of the crate is __________.
much force is needed to accelerate a 2-kg physics book to an acceleration
of 6 m/s to power of (2)?
jumbo jet cruises at a constant velocity when the total thrust of the
engines on the jet is 40,000 N. How much air resistance acts on the
42) A 10-N falling object encounters 10 N of air resistance. The magnitude of the net force on the object is __________.
A) 0 N. B) 4 N. C) 10 N. D) none of the above
Write True or False in the space provided.
43) The combination of all the forces that act on an object is called the net force. _______
44) The acceleration of an object is inversely proportional to the net force acting on it. _______
45) A steel ball and a wood ball of the same size are released together from the top of a tower. In the absence of air resistance they both would reach the ground at the same time. The reason for this is that the force on each ball is the same. _______
46) Excluding the force due to air pressure, there is only one force acting on a book lying at rest on a tabletop. _______
47) The force that supports the weight of a book lying at rest on a tabletop is called a normal force. _______
48) A fluid can be either a liquid or a gas. _______
49) The pascal is a unit of force. _______
50) It is possible for an object in free fall (no acceleration) to have zero acceleration. _______
51) Pressure is defined as the force one object exerts on another object. _______
52) The speed of an object dropped in air will continue to increase without limit. _______
On a separate sheet of paper, answer the following questions.
53) Explain why the acceleration of two freely-falling objects having different masses is the same. Is the force on each mass the same?
54) What two things does the force of friction basically depend on? In which direction does friction act? What would happen if friction were to act in the same direction as the motion?
55) Why is the teacher in Figure 5.8 unharmed? Is it important that the cement block have a lot of mass? Explain.
56) What is terminal speed? When a skydiver has reached terminal speed, what is the air resistance equal to? What is the skydiver's acceleration?
Answer the following questions in the space provided. Show all work.
57) You push with 20 N on a 10-kg block and there are no opposing forces. How fast will the block accelerate? _____________
58) You push with 20 N on a 10-kg block and there is a 10-N force of friction. How fast will the block accelerate? _____________
59) A 400,000-kg airplane in takeoff uses the 40,000 N thrust of each one of its four engines. What is the acceleration of the plane during takeoff?
60) An unbalanced force of 30 N gives an object an acceleration of 5.0 m/s to power of (2). What force would be needed to give it an acceleration of 1.0 m/s to power of (2)?
61) A certain unbalanced force gives a 5-kg object an acceleration of 2.0 m/s2. What acceleration would the same force give a 30-kg object?
62) A net force of 1.0 N acts on a 2.0 kg object, initially at rest, for 2.0 seconds. What is the distance the object moves during that time?
63) When air resistance on a falling skydiver builds up to 0.25 the weight of the skydiver, what is the acceleration of the skydiver?
64) Suppose that you exert 400 N horizontally on a 50-kg crate on a factory floor, when friction between the crate and the floor is 200 N. What is the acceleration of the crate?
65) A 50-kg block of cement is pulled upward (not sideways!) with a force of 800 N. What is the acceleration of the block?
66) Bronco the skydiver, whose mass is 50 kg, experiences 200 N of air resistance. What is the acceleration of his fall? _____________
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