Physical Science Chapter 2

You cannot exert a force on a wall A) if the wall resists. B) unless you put your mind to it. C) unless the wall simultaneously exerts the same amount of force on you.

C

A heavy rock and a light rock in free fall have the same acceleration because the A) force due to gravity is the same on each. B) air resistance is always zero in free fall. C) inertia of each is the same. D) ratio of force to mass is the same. E) none of the above

D

A math book and a science book are tied together with a length of string. With the string taut, one book is pushed off the edge of a table. As it falls, the other book is dragged horizontally across the table surface. With no friction, acceleration of the books is A) zero. B) g/2. C) g. D) between zero and g. E) greater than g.

D

A quick jerk on a sheet of paper beneath a box of cereal doesn't topple the box, which best illustrates that A) the box has no acceleration. B) there is an action-reaction pair of forces. C) gravity tends to hold the box secure. D) the box has inertia.

D

A skydiver who weighs 500 N reaches terminal velocity at 90 km/h. The air resistance on the skydiver is A) 90 N. B) 250 N. C) 410 N. D) 500 N. E) none of the above

D

After a ball tossed upward leaves your hand, the force of gravity on it A) no longer acts. B) gradually diminishes. C) gradually increases. D) remains constant. E) changes direction.

D

If gravity between the Sun and Earth suddenly vanished, Earth would move in A) a curved path. B) an outward spiral path. C) an inward spiral path. D) a straight-line path.

D

When a 500-N parachutist opens his chute and experiences 800 N of air resistance, the net force on him is A) 300 N downward. B) 500 N downward. C) 800 N downward. D) 300 N upward. E) 500 N upward.

D

If the mass of a cart is quickly loaded to have twice the mass while a propelling force remains constant, the cart's acceleration A) quadruples. B) doubles. C) stays the same. D) halves. E) none of these

D

If you are learning to juggle it would be good to slow the ball's acceleration. You can do this by using A) lighter balls. B) heavier balls. C) more balls. D) none of the above

D

What applied horizontal force will accelerate a 400-kg crate at 1 m/s2 across a factory floor against a friction force half its weight? A) 600 N B) 1600 N C) 2000 N D) 2400 N E) none of the above

D

The force required to maintain an object at a constant velocity in free space is equal to A) zero. B) the mass of the object. C) the weight of the object. D) the force required to stop it.

A

The net force on any object moving at constant velocity is A) zero. B) 10 meters per second squared. C) equal to its weight. D) about half its weight.

A

To say there is no such thing as only one force means A) there must also be an oppositely directed force. B) other forces, perhaps not evident, are there. C) gibberish.

A

When an apple that weighs 1 N is held at rest above your head, the net force on the apple is A) 0 N. B) 0.1 N. C) 1 N. D) 10 N. E) none of the above

A

A 10-N block and a 1-N block lie on a horizontal frictionless table. To push them with equal acceleration, we would have to push with A) equal forces on each block. B) 10 times as much force on the heavier block. C) 10 squared or 100 times as much force on the heavier block. D) one-tenth as much force on the heavier block. E) none of the above

B

A 10-kg block is pushed across a friction-free horizontal surface with a horizontal force of 20 N. The acceleration of the block is A) 1 m/s2. B) 2 m/s2. C) 5 m/s2. D) 10 m/s2. E) none of the above

B

A 10-kg block is pushed across a horizontal surface with a horizontal force of 30 N against a friction force of 10 N. The acceleration of the block is A) 1 m/s2. B) 2 m/s2. C) 5 m/s2. D) 10 m/s2. E) none of the above

B

A ball rests in the middle of a cart. When you quickly jerk the cart forward, the ball A) hits the front of the cart. B) hits the back of the cart. C) remains in the middle of the cart. D) all, depending on how quickly the cart is pulled

B

To steadily (constantly) increase the velocity of something requires a A) steadily increasing force. B) constant net force. C) decreasing force. D) none of the above

B

When a falling object has reached its terminal velocity, its acceleration is A) constant. B) zero. C) g.

B

When a rock thrown straight up reaches the exact top of its path, its velocity is A) zero and its acceleration is zero. B) zero and its acceleration is 10 m/s2. C) about 10 m/s and its acceleration is zero. D) about 10 m/s and its acceleration is 10 m/s2.

B

Inertia is defined as a A) force. B) property of matter. C) change in motion. D) none of the above

B) property of matter

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 book. B) 5 times as much as the force on the 1-kg book. C) 10 times as much as the force on the 1-kg book. D) zero.

C

A ball is thrown vertically into the air. Because of air resistance, its time coming down compared with its time going up is A) less. B) the same. C) more.

C

A block is dragged at constant velocity across a level surface by a force of 6 N. What is the force of friction between the block and the surface? A) less than 6 N B) more than 6 N C) 6 N D) not enough information

C

A 1000-kg car accelerates at 2 m/s2. What is the net force exerted on the car? A) 500 N B) 1000 N C) 1500 N D) 2000 N E) none of these

D

A ball tossed vertically upward reaches its highest point and then falls back to its starting point. During this up-and-down motion the acceleration of the ball is always A) in the direction of motion. B) opposite its velocity. C) directed upward. D) directed downward.

D

A big and a small person wish to parachute at equal terminal velocities. The big person should A) jump first. B) jump lightly. C) pull upward on the supporting strands to decrease the downward net force. D) get a larger parachute. E) none of the above

D

A falling object that has reached its terminal speed continues to gain A) acceleration. B) speed. C) both of these D) none of the above

D

A given net force propels an object along a straight-line path. If the mass were doubled, its acceleration would A) quadruple. B) double. C) stay the same. D) be half. E) none of the above

D

Which object has zero acceleration? A) one at rest B) one moving at constant velocity C) one in mechanical equilibrium D) all of the above E) none of the above

D

A 1-kg ball is thrown straight up at 10 m/s. Neglecting air resistance, the net force that acts on the ball when it is halfway to the top of its path is A) 1/2 N. B) 1 N. C) 5 N. D) 7.5 N. E) 10 N.

E

A 10-kg brick and a 1-kg book are dropped in a vacuum. The acceleration of the 10-kg brick is A) the same as that of the 1-kg book. B) 5 times as much as for the 1-kg book. C) 10 times as much as for the 1-kg book. D) zero.

A

A 10-kg block is pushed across a horizontal surface with a horizontal force of 20 N against a friction force of 10 N. The acceleration of the block is A) 1 m/s2. B) 2 m/s2. C) 5 m/s2. D) 10 m/s2. E) none of the above

A

A ball is thrown upward and caught when it returns. When air resistance affects the ball, compared with the initial upward speed, the speed of the ball when caught is A) less. B) the same. C) more.

A

A ball is thrown vertically upward. At the top of its vertical path, its velocity is A) 0 m/s. B) 10 m/s. C) between 0 m/s and 10 m/s. D) greater than 10 m/s. E) none of the above

A

A bird sitting on the limb of a tree is moving about 30 km/s with respect to the Sun. If the bird takes 1 second to drop down to a worm below, the worm would be 30 km downrange from the bird when it reached the ground. This faulty reasoning is best countered with Newton's A) law of inertia. B) law of gravity. C) laws of motion. D) none of the above

A

A car by itself is capable of a certain maximum acceleration. When it tows a car of the same mass, its maximum acceleration is A) half. B) one-third. C) one-fourth. D) the same. E) none of these

A

A hockey puck slides across a frozen pond. If ice friction and air resistance are neglected, the force needed to keep the puck sliding at constant velocity is A) 0 N. B) equal to the weight of the puck. C) the weight of the puck divided by the mass of the puck. D) the mass of the puck multiplied by 10 m/s2. E) none of the above

A

A light woman and a heavy man jump from an airplane at the same time and open their same—size parachutes at the same time. Which person reaches a state of zero acceleration first? A) the light woman B) the heavy man C) both at the same time D) not enough information

A

A sack of potatoes weighing 200 N falls from an airplane. As the velocity of fall increases, air resistance also increases. When air resistance equals 200 N, the sack's acceleration is A) 0 m/s2. B) 5 m/s2. C) 10 m/s2. D) infinite. E) none of the above

A

Action and reaction forces are parts of A) a single interaction. B) a pair of interactions. C) multiple interactions.

A

An huge bear and a leaf fall from a tree through the air to the ground below. The force of air resistance is greater on the A) bear. B) leaf. C) same on each

A

Earth exerts a force on the Moon. These two bodies make up A) one interaction. B) two interactions. C) multiple interactions.

A

How many forces act on an upwardly tossed coin when it gets to the top of its path? A) one; the force due to gravity B) two; gravity and the force in the coin itself C) three; gravity, the coin's internal force, and a turnaround force D) none of the above

A

If you carry a heavy bag of groceries and bang your hand against the wall, the concept that best explains why your hand hurts is A) inertia. B) gravity. C) resistance. D) none of the above

A

If you jump vertically while inside a fast-moving train that is slowing down, you land A) a bit ahead of your original position. B) at your original position. C) a bit behind your original position.

A

If your automobile runs out of fuel while driving, the engine stops. You don't come to an abrupt stop because of A) inertia. B) gravity. C) resistance. D) the principle of continuation.

A

A car by itself is capable of a certain maximum acceleration. When it tows a twice-asmassive car, its maximum acceleration is A) one-half. B) one-third. C) one-fourth. D) the same. E) none of these

B

A constant net force on a railroad car produces constant A) velocity. B) acceleration. C) both of these D) neither of these

B

A given net force propels an object along a straight-line path. If the net force were doubled, its acceleration would A) quadruple. B) double. C) stay the same. D) be half. E) none of the above

B

A heavy block at rest is suspended by a vertical rope. When the block is raised at constant velocity, the rope tension A) is less than its weight. B) equals its weight. C) is greater than its weight.

B

A heavy object and a light object in a vacuum are dropped at the same time from rest. The heavy object reaches the ground A) sooner than the light object. B) at the same time as the light object. C) later than the light object.

B

A martial arts person breaks a board with a blow of 3000 N. The force that acts on the hand is A) less than 3000 N. B) 3000 N. C) more than 3000 N. D) not enough information

B

A moving van with a stone lightly glued to the midpoint of its ceiling smoothly moves at constant velocity. When the glue gives way, the stone falls and hits the floor A) ahead of the midpoint of the ceiling. B) exactly below the midpoint of the ceiling. C) behind the midpoint of the ceiling. D) none of the above

B

A pair of tennis balls fall through the air from a tall building. One ball is regular and the other is filled with lead pellets. Air resistance just before they hit is greater for the A) regular ball. B) lead-filled ball. C) same for both

B

A pair of tennis balls fall through the air from a tall building. One ball is regular and the other is filled with lead pellets. The ball to reach the ground first is the A) regular ball. B) lead-filled ball. C) same for both

B

A push on a 1-kg brick accelerates the brick. Neglecting friction, to equally accelerate a 10-kg brick requires the force to be A) just as much. B) 10 times as much. C) 100 times as much. D) one-tenth as much. E) none of the above

B

A skydiver jumps from a high-flying plane. As her velocity of fall increases, her acceleration A) increases. B) decreases. C) remains unchanged regardless of air resistance.

B

A stone is thrown vertically upward. At the top of its vertical path its acceleration is A) zero. B) 10 m/s2. C) somewhat less than 10 m/s2. D) undetermined.

B

A stone is thrown vertically upward. At the top of its vertical path the force acting on it is A) zero. B) only the force due to gravity. C) due to air resistance. D) both due to gravity and air resistance.

B

An iron ball and a wooden ball of the same size are dropped from a tall tower. Taking air resistance into consideration, the object to hit the ground first will be the A) lighter wooden ball. B) heavier iron ball. C) both hit at the same time. D) not enough information

B

As drops fall from a leaky faucet they become A) closer together as they fall. B) farther apart as they fall. C) a fixed distance apart as they fall. D) none of the above

B

If an object falls with constant acceleration, the velocity of the object must A) be constant also. B) continually change by the same amount each second. C) continually change by varying amounts, depending on its speed. D) continually decrease. E) none of the above

B

If an object's mass is decreasing while a constant force is applied to the object, the acceleration A) decreases. B) increases. C) remains the same

B

If the mass of an object does not change, a constant net force on the object produces constant A) velocity. B) acceleration. C) both of these D) none of the above

B

If you drop an object, it will accelerate downward at a rate of 10 m/s2. If you instead throw it downward, its acceleration (in the absence of air resistance will be A) less than 10 m/s2. B) 10 m/s2. C) greater than 10 m/s2.

B

Jake pulls on a 25-kg cart with a constant force of 50 N. What is the wagon's acceleration? A) 0.2 m/s2 B) 2.0 m/s2 C) 5 m/s2 D) 20 m/s2 E) 200 m/s2

B

Lillian pulls on a 10-kg wagon with a constant force of 30 N. What is the wagon's acceleration? A) 0.3 m/s2 B) 3.0 m/s2 C) 10 m/s2 D) 30 m/s2 E) 300 m/s2

B

When an object falls through the air, as velocity increases the net force A) increases. B) decreases. C) remains the same whether in air or in a vacuum.

B

When dishes remain on a table when you yank the tablecloth beneath them, you're demonstrating A) friction. B) inertia. C) constant motion. D) ΣF = 0.

B

When you rub your hands together, you A) can push harder on one hand than the other. B) cannot push harder on one hand than the other. C) need more information

B

When you toss a coin straight up, it moves upward, turns around, and drops. During all this time the acceleration of the coin is A) upward and constant. B) downward and constant. C) first decreasing, then increasing. D) zero throughout its up and down motion.

B

Whirl a rock at the end of a string and it follows a circular path. If the string breaks, the rock tends at first to A) continue in a circular path. B) follow a straight-line path. C) spiral inward. D) fall straight downward.

B

When you step off a bus moving at 2 m/s, your horizontal speed when you meet the ground is A) zero. B) less than 2 m/s but greater than zero. C) about 2 m/s. D) greater than 2 m/s.

C

You drive your car along the highway at a constant 60 km/h and apply the brakes until the car slows to 40 km/h. If at that moment you suddenly release the brakes, the car tends to A) momentarily regain its higher initial speed. B) continue moving at 40 km/h. C) decrease in speed if no other forces act.

B

You're in a fast-moving train traveling at constant velocity. If you jump straight up you land A) slightly ahead of your original position. B) at your original position. C) slightly behind your original position.

B

A commercial jet has a mass of 5000 kg. During takeoff the thrust of its engine is 10,000 N, producing an acceleration of A) 0.5 m/s2. B) 1 m/s2. C) 2 m/s2. D) 4 m/s2. E) none of the above

C

A force of 1 N accelerates a 1-kg mass at 1 m/s2. The acceleration of a 2-kg mass 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

C

A heavy block at rest is suspended by a vertical rope. When the block is accelerated upward by the rope, the rope tension A) is less than its weight. B) equals its weight. C) is greater than its weight.

C

A jumbo jet of mass 100,000 kg during takeoff experience a thrust for each of its four engines of 50,000 N, producing an acceleration of A) 0.5 m/s2. B) 1 m/s2. C) 2 m/s2. D) 4 m/s2. E) none of the above

C

A parachutist steps from a hovering helicopter and falls for 5 s before reaching terminal velocity. During this 5-s interval, her acceleration A) is constant. B) increases. C) decreases. D) is zero. E) none of the above

C

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. The particle with both forces acting A) is brought to a rapid halt. B) decelerates gradually to a halt. C) continues at the same speed it had before encountering the second force. D) theoretically tends to accelerate toward the speed of light. E) none of the above

C

A player hits a ball with a bat. If one part of the interaction is the bat against the ball, the other part is the A) air resistance on the ball. B) weight of the ball. C) ball against the bat. D) grip of the player's hand against the ball. E) none of the above

C

A space probe in remote outer space continues moving A) because some kind of force acts on it. B) in a curved path. C) even though no force acts on it. D) due to gravity.

C

A tow truck exerts a force of 3000 N on a car that accelerates at 2 m/s2. What is the mass of the car? A) 500 kg B) 1000 kg C) 1500 kg D) 3000 kg E) none of these

C

An object in motion tends to remain in motion A) because of a force within the object. B) only when an external force acts on it. C) without the need of a force. D) due to its nature.

C

Earth moves about 30 km/s relative to the Sun. When you jump upward in front of a wall, the wall doesn't slam into you at 30 km/s because the wall A) has too little gravity to influence you. B) moves in the opposite direction to you. C) and you move at the same horizontal speed, before, during, and after your jump. D) has negligible inertia compared with the Sun.

C

If a non-rotating object has no acceleration, then we can say for certain that it is A) at rest. B) moving at constant non-zero velocity. C) in mechanical equilibrium. D) all of the above E) none of the above

C

If an object's mass decreases while a constant force acts on it, the acceleration A) decreases. B) remains the same. C) increases. D) will be zero.

C

If you jump straight up while inside a fast-moving train that gains speed, you land A) slightly ahead of your original position. B) at your original position. C) slightly behind your original position.

C

Newton's second law focuses on A) speed. B) velocity. C) acceleration. D) none of the above

C

The acceleration of a rocket increases 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 fuel is burned. C) the mass of the rocket decreases as fuel is burned.

C

The air resistance of falling is greatly affected by an object's frontal area and A) mass. B) weight. C) speed.

C

When a baseball player hits a ball with a force of 1000 N, the ball exerts a force on the bat of A) less than 1000 N. B) more than 1000 N. C) 1000 N.

C

When a rocket ship gaining speed in remote, gravity-free outer space runs out of fuel, it A) gains speed for a short time, then slows down to a constant velocity. B) gains speed for a short time, slows down, and eventually stops. C) no longer gains speed. D) comes to a quick stop.

C

When an apple that weighs 1 N is dropped and freely falls, the net force on the apple is A) 0 N. B) 0.1 N. C) 1 N. D) 10 N. E) none of the above

C

When you toss a ball upward, after the ball leaves your hand A) the force of your hand moves it up and gradually changes direction. B) the upward force changes direction at the top of the path. C) we see that force and velocity are essentially the same thing. D) none of the above

D

While a car travels around a circular track at constant speed, its A) acceleration is zero. B) velocity is zero. C) both of these D) none of the above

D