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Newton’s Laws Practice 1 • • • • • The kilogram is a measure of an object’s: A) weight B) gravity C) force D) mass 2 • Whirl a rock at the end of a string and it follows a circular path. If the string breaks, the tendency is of the rock is to: • A) continue to follow a circular path • B) follow a straight line path 3 • A sheet of paper can be withdrawn from under a milk carton without toppling it as long as the sheet is pulled quickly. This demonstrates: • A) gravity tends to hold the carton to the ground • B) the carton has inertia • C) for every action there’s an equal reaction 4 • • • • Your weight is: A) a property of mechanical equilibrium B) actually your mass C) the gravitational attraction between your body and the earth 5 • One object has twice as much mass as another object, and also has twice as much: • A) volume • B) velocity • C) inertia • D) gravitational acceleration 6 • Jupiter has 3 times the gravitational force of Earth. So on Jupiter, a 100kg object would have a mass of: • A) 100kg • B) 30kg • C) 300kg • D) 600kg 7 • An object weighs 20 N on the Earth, another object weighs 20 N on the moon. Which object has more mass? • A) Object on the Earth • B) Object on the Moon • C) They have the same mass. 8 • • • • The law of inertia applies to: A) objects at rest B) objects in motion C) both moving and nonmoving objects 9 • A force is a vector quantity because it has both: • A) mass and acceleration • B) action and reaction counterparts • C) magnitude and direction 10 • 10kg brick and a 1kg brick are dropped in a vacuum, the force of gravity on the 10kg brick is: • A) zero • B) 10 times as much as the 1kg brick • C) the same as the 1kg brick 11 • 10kg brick and a 1kg brick are dropped in a vacuum, the acceleration due to gravity on the 10kg brick is: • A) zero • B) 10 times as much as the 1kg brick • C) the same as the 1kg brick 12 • An object is propelled along a straight-line path. If it’s force were doubled, then it’s acceleration would: • A) halve • B) quadruple • C) double • D) stay the same 13 • An object is propelled in a straight-line path by a force. If the mass of the object is somehow doubles, it’s acceleration: • A) halves • B) quadruples • C) doubles • D) stays the same 14 • An object is pulled northward at 20 N and southward at 15 N. What magnitude of the net force? A. B. C. D. 5N 35 N 0N 10 N 15 • A 10N falling object encounters 10N of air resistance. The magnitude of the net force is: • A) 100N • B) 10N • C) 0N • D) Infinite 16 • An apple is held at rest above your head. The magnitude of the net force of the apple is: • A) 10N • B) 0N • C) 100N • D) between 10N and 0N 17 • Which has zero acceleration? An object_____ • A) at rest • B) changing its direction • C) changing its speed • D) all of these 18 • Whenever the net force on an object is zero, the acceleration • A) may be zero • B) is zero • C) is not zero 19 • A car has a mass of 3000kg and accelerates at 2 m/s/s. What is the magnitude of the force exerted on the car? A. B. C. D. 1500N 3000N 6000N 2000N 20 • A tow truck exerts a 2 m/s/s acceleration on a car with a force of 300N. The mass of the car is • A) 600 kg • B) 3000 kg • C) 150 kg • D) 1500 kg 21 • A girl pulls a 10kg wagon with a constant force of 300N. What is the wagon’s acceleration in m/s/s? • A) .3 • B) 3000 • C) 30 • D) 1/30 22 • Whenever an object exerts a force on another object, the second object exerts a force of the same magnitude but in the opposite direction. • A) Always true • B) Sometimes true • C) Usually true 23 • A high school student hits a nail with a hammer. During the collision there is a force: • A) On the hammer but not the nail • B) On the nail but not the hammer • C) On both hammer and nail 24 • • • • • Forces always occur: A) in singles B) in pairs C) in triplets D) in space 25 • A rocket is able to propel itself in the vacuum of space by firing its engines. The force that propels the rocket is: • A) The exhaust gasses pushing on space • B) The exhaust gasses heating up the ship • C) The exhaust gasses rushing away from the ship 26 • An archer shoots an arrow. Consider the action force to be the bowstring pushing against the arrow. The reaction force is: • A) air resistance pushing against the arrow • B) the grip of the archers hand on the bow • C) the push of the arrow against the bowstring • D) none of these 27 • A baseball player bats a ball with a force of 1000N, the ball exerts a reaction force against the bat of • A) 100N • B) 1000N • C) A little less than 1000N • D) Not enough information 28 • As the ball falls, the action force is the mass of the earth pulling on the ball. The reaction force is • A) the ball’s pull on the earth • B) nonexistent in this case • C) the ball pushing on the ground • D) air resistance 29 • A karate chop delivers a blow of 3,000N to a board that breaks. The force that acts on the hand is actually: • A) more than 3000N • B) less than 3000N • C) exactly 3000N • D) depends if the board was oak or ash 30 • Arnold Strongman and Suzy Small pull hard in opposite directions in a tug of war. The greatest force on the rope is exerted by: • A) Suzy, suprisingly • B) Arnold, of course • C) both the same 31 • Which of the following is not an acceleration? A. Stopping your bike at an intersection. B. Riding your bike at a constant speed around a corner. C. Slowing your bike down as you reach the top of the hill. D. Riding your bike faster as you ride down the hill. E. Riding your bike straight down the street at a constant speed. 32 • ___________ is the pull that all objects exert on each other. A. B. C. D. Resistance Friction Inertia Gravity 33 • At the surface of Jupiter’s moon Io, the acceleration due to gravity is 2.50 m/s/s. A watermelon weights 44.0 N at the surface of the earth. What is the mass on the earth’s surface? • What are its mass and weight on the surface of Io? 34 • What is the net force required to give an automobile of mass 1600. kg an acceleration of 4.5 m/s/s? 35 • During a test crash, an air bag inflates to stop a dummy’s forward motion. The dummy’s mass is 75.0 kg. If the net force on the dummy is 825. N toward the rear of the car, what is the dummy’s acceleration? 36 • A bicycle takes 8.0 seconds to accelerate at a constant rate from rest to a speed of 4.0 m/s. If the mass of the bicycle and rider together is 85. kg, what is the net force acting on the bicycle? 37 • You are waiting in line to use the diving board at your local pool. While watching people dive into the pool from the board, you realize that using a diving board to spring into the air before a dive is a good example of Newton’s third law of motion. Explain how a diving board illustrates Newton’s 3rd law. 38 • If bullets are fired from an airplane in the direction of its motion . . . A. the speed of the airplane will increase. B. the speed of the airplane will decrease. C. there will be no change in the speed of the airplane. D. the speed will change but the velocity will remain the same. 39 • Which exerts more force, the Earth pulling on the moon or the moon pulling on the Earth? Explain. 40 • When a heavy football player and a light one run into each other, which player hits the other with more force? Explain. Which one is hurt more by the collision? Explain. 41 • Equilibrium is the state of motion where A. All forces on an object are balanced. B. An object can be accelerating or sitting at rest. C. Both A and B D. Neither A nor B 42 • According to Newton’s second law of motion, if the net force acting on the object increases while the mass of the object remains constant, what happens to the acceleration? A. B. C. D. Acceleration decreases Acceleration increases Acceleration remains the same Acceleration is independent of mass 43 • In order to start a grocery cart in motion, you must exert 72.0 Newtons of force on the handle. The mass of the grocery cart is 61.0 kg. How much force does the cart exert on your hand as you accelerate it forward? A. B. C. D. 4400 N 1.2 N 72.0 N 0N 44 • How much does a 9.8 kg pail of water weigh? A. B. C. D. 9.80 kg 96.0 N 9.80 N 96.0 kg 45 • When an object is not in equilibrium, what kind of motion can it have? A. B. C. D. Circular Accelerating Decelerating All of the above 46 • A helicopter weighs 12,800 N, how much force must its rotors exert on the air in order to start it rising into the air from its landing pad? 47 • A 2 kg box sits on a 3 kg box which sits on a 5 kg box. The 5 kg box rests on a table top. What is the normal force exerted on the 5 kg box by the table top? A. B. C. D. 19.6 N 29.4 N 49 N 98 N 48 • A 2 kg box sits on a 3 kg box which sits on a 5 kg box. The 5 kg box rests on a table top. What is the normal force exerted by the 5 kg box on the 3 kg box? A. B. C. D. 19.6 N 29.4 N 49 N 98 N 49 • A car pulls on a rope tied to a tree with a force of 1000 N. Which of the following is not true? A. The rope pulls on the tree with a force of 1000 newtons. B. The tree pulls on the rope with a force of 1000 newtons. C. The tension in the rope is 2000 newtons. D. The tension in the rope is 1000 newtons. 50 • A free-body diagram of a ball in free fall would show A. a downward arrow to represent the force of air resistance. B. only a downward arrow to represent the force of gravity. C. a downward arrow to represent the force of gravity and an upward arrow to represent the force of air resistance. D. an upward arrow to represent the force of gravity and a downward arrow to represent the force of air resistance. 51 • Which of the following is the tendency of an object to maintain its state of motion? A. B. C. D. Acceleration Inertia Force Velocity 52 • If a nonzero net force is acting on an object, then the object is definitely A. B. C. D. at rest. moving with a constant velocity. being accelerated. losing mass. 53 • According to Newton’s 2nd law, when the same force is applied to two objects of different masses, A. the object with greater mass will experience a great acceleration and the object with less mass will experience an even greater acceleration. B. the object with greater mass will experience a smaller acceleration and the object with less mass will experience a greater acceleration. C. the object with greater mass will experience a greater acceleration and the object with less mass will experience a smaller acceleration. D. the object with greater mass will experience a smaller acceleration and the object with less mass will experience an even smaller acceleration. 54 • A hammer drives a nail into a piece of wood. Identify an action-reaction pair. A. The nail exerts a force on the hammer; the hammer exerts a force on the wood. B. The hammer exerts a force on the nail; the nail exerts a force on the wood. C. The hammer exerts a force on the nail; the nail exerts a force on the hammer. D. The hammer exerts a force on the nail; the hammer exerts a force on the wood. 55 • When a car is moving, what happens to the velocity and acceleration of the car if the air resistance becomes equal to the force acting in the opposite direction? 56 • A force of 10. N applied to a given mass accelerates is at 1.0 m/s/s. The same force applied to a mass one-half as great would produce an acceleration of A. B. C. D. 1.0 m/s/s 2.0 m/s/s 0.50 m/s/s 4.0 m/s/s 57 • A certain net force causes a 10. kg mass to accelerate at 20. m/s/s. The same force will cause a 5.0 kg mass to accelerate at A. B. C. D. 9.8 m/s/s 10. m/s/s 25. m/s/s 40. m/s/s 58 • If the sum of all the forces acting on a car is zero, the car A. must be at rest. B. must be moving at a constant speed. C. may be at rest or moving at a constant speed. D. must be accelerating. 59 • Which of the following is equal to one Newton? A. B. C. D. Kg m/s Kg m Kg m/s/s Kg/m/s/s 60 • The weight of an apple to closest to A. B. C. D. 1N 9.8 N 19.6 N 980 N 61 • On the surface of a distant planet a 5 kg mass weighs 20 N. What is the acceleration due to gravity there? A. B. C. D. 0.25 m/s/s 1 m/s/s 4 m/s/s 15 m/s/s 62 • If we know an object is moving at constant velocity, we may assume A. B. C. D. E. the net force acting on the object is zero. there are no forces acting on the object. the object is accelerating. the object is losing mass. the net force acting on the object isn’t zero. 63 • A 7.0 kg bowling ball experiences a net force of 5.0 N. What will be its acceleration? A. B. C. D. E. 35 m/s/s 7.0 m/s/s 5.0 m/s/s 0.71 m/s/s 0.52 m/s/s 64 • Rita accelerates a 0.40 kg ball from rest to 9.0 m/s during the 0.15 seconds in which her foot is in contact with the ball. What average force does she apply to the ball during the kick? A. B. C. D. E. 48 N 72 N 24 N 60 N 76 N 65 • As a 3.0 kg bucket is being lowered into a 10 meter deep well, starting from the top, the tension in the rope is 9.8 N. The acceleration of the bucket will be A. B. C. D. E. 6.5 m/s/s downward 9.8 m/s/s downward zero 3.3 m/s/s upward 6.5 m/s/s upward 66 • A karate master strikes a board with an initial velocity of 10.0 m/s, decreasing to 1.0 m/s as his hand passes through the board. If the time of contact with the board is 0.002 seconds and the mass of the coordinated hand and arm is 1.0 kg, what is the force exerted on the board? A. -1000 N B. 1800 N C. -2700 N D. -4500 N E. 4500 N 67 • In which case would you have the largest mass of gold? If your chunk of gold weighed 1 N on the A. moon. B. Earth. C. planet Jupiter. 68 • An object is propelled along a straight-line path by a force. If the net force were doubled, the object’s acceleration would be A. B. C. D. E. half as much. twice as much. the same. four times as much. None of these 69 • An object is propelled along a straight line path in space by a force. If the mass of the object somehow becomes twice as much, its acceleration A. B. C. D. E. quadruples. doubles. stays the same. halves. None of these 70 • The force of friction on a sliding object is 10 newtons. The applied force needed to maintain a constant velocity is A. more than 10 N. B. less than 10 N. C. 10 N. 71 • An apple at rest weighs 1 N. The net force on the apple when it is in free fall is A. B. C. D. E. 0 N. 0.1 N 1N 9.8 N None of these 72 • An object following a straight line path at constant speed A. has a net force acting upon it in the direction of motion. B. has zero acceleration. C. has no forces acting on it. D. both B & C E. None of these. 73 • A rocket becomes progressively easier to accelerate as it travels upward from the ground mainly because A. gravity becomes weaker with increased distance. B. the applied force on the rocket increases as burning of fuel progresses. C. the mass of the rocket decreases as fuel is burned. 74 • A rock is thrown vertically into the air. At the top of its path, its acceleration in meters per second per second is A. B. C. D. zero. 9.8. between 0 and 9.8. greater than 9.8. 75 • Suppose a particle is being accelerated through space by a 10 N force. Suddenly the particle encounters a second force of 10 N in the opposite direction from the first force. The particle with both forces acting on it A. is brought to a rapid halt. B. decelerates gradually to a halt. C. continues at the speed it had when it encountered the second force. D. theoretically tends to accelerate toward the speed of light. E. None of these 76 • A 1 kg rock that weighs 9.8 N is thrown straight upward at 20 m/s. Neglecting air resistance, the net force that acts on it when it is half way to the top of its path is A. less than 9.8 N. B. 9.8 N. C. more than 9.8 N. 77 • If an object of constant mass experiences a constant net force, it will have a constant A. B. C. D. velocity. speed. acceleration. position. 78 • If less horizontal force is applied to a sliding object than is needed to maintain constant velocity A. the object accelerates in the direction of the applied force. B. the friction force increases. C. the object eventually slides to a stop. D. None of these 79. A stoplight 20 m to the west turns yellow. Your car is traveling west at 12 m/s. You hit the brakes and slows down at a rate of 6.0 m/s2. Your car stops before it reaches the stoplight (which is considered to be at “zero”). A student in a physics class made a picture of the situation but did not include the signs of the variables. x to = 0 s xo = __ 20 m vo = __ 12 m/s a = __ 6.0 m/s2 What are the signs of the three missing variables? 1 2 3 4 5 xo + + + + – vo – – + + – a – + – + + 80. A stoplight 20 m to the west turns yellow. Your car is traveling west at 12 m/s. You hit the brakes and slow down at a rate of 6.0 m/s2. Your car stops before it reaches the stoplight (which is considered to be at “zero”). A student in a physics class made a picture of this. x to = 0 s xo = + 20 m vo = – 12 m/s a = – 6.0 m/s2 Which of the following is labeled wrong? 1 2 3 4 5 xo vo a a & vo all of the values are correct 81. The motion of a car is represented with the motion diagram below. vfinal vinitial a x Which graph best matches the motion diagram? 1 2v v t 3 v t t t 4v 5 No graph represents the motion correctly 82. A stoplight 20 m to the west turns yellow. Your car is traveling west at 12 m/s. You hit the brakes and slows down at a rate of 6.0 m/s2. Your car stops before it reaches the stoplight (which is considered to be at “zero”). Which graph is the best representation of the car’s motion? 1 2x x 3 x t t 4 x t t 5 No graph represents the motion correctly 83. A bicycle is moving on the road. Its motion is described by the graph below. t v Below is a mathematical description of the same motion. What should the signs of vo and a be to be consistent with the above graphical description? 1 2 3 4 vo + + – – a – + + – 84. Alan sees the following three diagrams next to each other in his physics book. v x a t A t B t C Are these three diagrams consistent with each other? 1. Yes, all three diagrams are consistent. 2. No, Diagram A is not consistent with the other two. 3. No, Diagram B is not consistent with the other two. 4. No, Diagram C is not consistent with the other two. 5. None of the diagrams are consistent.