Q&A Hero

Q: 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.

Q: 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.

Q: 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

Q: 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.

Q: 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.

Q: 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

Q: 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

Q: 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.

Q: 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

Q: 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.

Q: 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.

Q: 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.

Q: 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

Q: 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.

Q: 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

Q: 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

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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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.

Q: 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.

Q: 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.

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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

Q: 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.

Q: 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

Q: 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

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

Q: 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

Q: 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

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

Q: 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.

Q: 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.

Q: 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.

Q: 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.

Q: 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

Q: 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.

Q: 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.

Q: 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

Q: 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.

Q: 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

Q: 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

Q: 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.

Q: 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

Q: 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.

Q: 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.

Q: 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.

Q: 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.

Q: 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.

Q: 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.

Q: 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.

Q: 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

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

Q: Distinguish between the concepts of velocity and acceleration, using a bowling ball's behavior as an example for each.

Q: What is the difference between speed, velocity, and instantaneous velocity? Give examples of each.

Q: Give three examples of the equilibrium rule that are not cited in the textbook.

Q: What is the meaning of the expression ΣF = 0?

Q: Distinguish between the concepts of mass and weight. Which is more fundamental, and why?

Q: Once a basketball player's feet are off the floor in making a jump, the jumper's acceleration A) depends on launch speed. B) is usually greater for taller players. C) varies with body orientation. D) is g; no more, no less. E) all of the above

Q: On the surface of the Moon where acceleration due to gravity is less, a person's hang time would be A) longer. B) shorter. C) the same as on Earth.

Q: The vertical height attained by a basketball player who achieves a hang time of a full 1 s is about A) 0.8 m. B) 1 m. C) 1.2 m. D) 2.5 m. E) more than 2.5 m.

Q: Phil Physiker standing at the edge of a cliff throws one ball straight up and another ball straight down, both with the same speed. Both balls hit the ground at A) different speeds. B) the same speed in the same time. C) the same speed in different times. D) none of the above

Q: Phil Physiker standing at the edge of a cliff throws one ball straight up and another ball straight down, both with the same speed. Neglecting air resistance, which ball hits the ground below with the greater speed? A) the one thrown upward B) the one thrown downward C) neither, both hit with the same speed

Q: If a freely-falling object were somehow equipped with a speedometer on a planet where the acceleration due to gravity is 20 m/s2, then its speed reading would increase each second by A) 10 m/s. B) 20 m/s. C) 30 m/s. D) 40 m/s. E) depends on its initial speed

Q: If you toss a ball straight upward at 40 m/s with no air resistance, 6 seconds later its speed is A) zero. B) 10 m/s. C) 20 m/s. D) 30 m/s E) 40 m/s.

Q: If you toss a ball straight upward at 40 m/s with no air resistance, one second after it reaches the top of its path its speed is A) zero. B) 10 m/s. C) 20 m/s. D) 30 m/s E) 40 m/s.