Q&A Hero

Q: If you toss a ball straight upward at 40 m/s with no air resistance, one second before 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.

Q: If you toss a ball straight upward at 40 m/s, with no air resistance it returns to you at a speed of A) zero. B) 10 m/s. C) 40 m/s. D) more than 40 m/s.

Q: What is the acceleration of a scooter that maintains a constant velocity of 15 m/s for 10 s? A) 0 m/s2 B) 0.15 m/s2 C) 1.5 m/s2 D) 15 m/s2

Q: The acceleration of a vertically-thrown ball at the top of its path is A) zero. B) 10 m/s2. C) between zero and 10 m/s2. D) dependent on the mass of the ball.

Q: The speed of a vertically-thrown ball at the top of its path is A) zero. B) 10 m/s2. C) between zero and 10 m/s2. D) dependent on the mass of the ball.

Q: An object travels 8 m in the 1st second of travel, 8 m again during the 2nd second of travel, and 8 m again during the 3rd second. Its acceleration is A) 0 m/s2. B) 5 m/s2. C) 8 m/s2. D) 10 m/s2. E) more than 10 m/s2.

Q: The acceleration of a cart rolling down an inclined plane (a ramp) A) is approximately constant. B) increases with time. C) decreases with time.

Q: If a freely-falling object were somehow equipped with a speedometer, its speed reading would increase each second by about A) 5 m/s. B) 10 m/s. C) 15 m/s. D) a variable amount.

Q: A freely-falling object has a speed of 30 m/s at one instant. Exactly 2 seconds later its speed will be A) the same. B) 40 m/s. C) 50 m/s. D) more than 50 m/s.

Q: An object in free fall has a speed of 60 m/s. One second later its speed is A) 10 m/s. B) 30 m/s. C) 60 m/s. D) 70 m/s.

Q: Six seconds after starting from rest, a freely-falling baseball has a speed of A) 10 m/s. B) 30 m/s. C) 60 m/s. D) 70 m/s.

Q: Ten seconds after starting from rest, a freely-falling baseball will have a speed of about A) 10 m/s. B) 50 m/s. C) 100 m/s. D) 500 m/s. E) more than 500 m/s.

Q: At the end of 2 seconds an apple freely falling from rest has a speed of A) 1 m/s. B) 5 m/s. C) 10 m/s. D) more than 10 m/s.

Q: At the end of 1/2 second an apple freely falling from rest has a speed of A) 1 m/s. B) 5 m/s. C) 10 m/s. D) more than 10 m/s.

Q: Any falling object that gains a velocity of 10 m/s each second has an acceleration of A) 10 m/s. B) 10 m/s2. C) both of these D) none of the above

Q: The gain in speed each second for a freely-falling object is about A) 0 m/s. B) 5 m/s. C) 10 m/s. D) 20 m/s. E) depends on the initial speed.

Q: During each second of free fall, the speed of an object A) increases by the same amount. B) changes by increasing amounts each second. C) remains constant. D) doubles each second.

Q: As an object freely falls, its A) velocity increases. B) acceleration increases. C) both of these D) none of the above

Q: A motor scooter undergoes acceleration when it A) gains speed. B) decreases speed. C) changes direction. D) all of the above

Q: The acceleration of a Tesla that maintains a constant velocity of 120 km/h over a time of one-half hour is A) 60 km/h. B) 120 km/h. C) 240 km/h. D) zero because of no change in velocity.

Q: If a ball rolls down an inclined plane and gains 4 m/s each second it rolls, its acceleration is A) one half of 4 m/s. B) one half of 4 m/s2. C) 4 m/s2. D) 10 m/s2.

Q: When a ball increases in speed by the same amount each second, its acceleration A) also increases each second. B) decreases each second. C) is constant. D) varies.

Q: A good tutor will be correct in saying that velocity and acceleration are A) the same concept, but expressed differently. B) rates of one another. C) expressions for changing speeds. D) different concepts.

Q: Acceleration and velocity are A) different names for the same idea. B) very different from each other. C) concepts developed by Aristotle. D) none of the above

Q: The average speed of a horse that gallops a distance of 10 km in a time of 30 min is A) 10 km/h. B) 20 km/h. C) 30 km/h. D) more than 30 km/h.

Q: When Jean hikes a distance of 1 km in a time of one-half hour her average speed is A) nearly 1 km/h. B) 1 km/h. C) slightly more than 1 km/h. D) 2 km/h.

Q: The average speed of Daisy running a distance of 2 km in a time of one-half hour is A) 1 km/h. B) 2 km/h. C) 4 km/h. D) more than 4 km/h.

Q: Emily Easygo can paddle her canoe at 8 m/s in still water. With this speed she then paddles upstream in a river that runs downstream at 6 m/s. Her friend sitting on shore sees her speed as A) 2 m/s. B) 6 m/s. C) 8 m/s. D) 10 m/s.

Q: In a dream you're in a car traveling at 50 km/h and you bump into another car traveling toward you at 48 km/h. The speed of impact is A) 48 km/h. B) 50 km/h. C) 98 km/h. D) 2400 km/h.

Q: You're driving in a car at 50 km/h and bump into a car ahead traveling at 48 km/h in the same direction. The speed of impact is A) zero. B) 2 km/h. C) 48 km/h. D) 50 km/h. E) 98 km/h.

Q: While in an airplane flying at 100 km/h you look down from the window and spot another airplane flying at the same speed in the opposite direction. Relative to you, the speed of the spotted plane is A) zero. B) 100 km/h. C) 150 km/h. D) 200 km/h.

Q: You're lying on the sand on a breezy day when a pesky fly wishes to join you. The breeze is blowing at a steady 1 m/s. If the fly wishes to land on you it should hover over you while flying A) about 2 m/s relative to the breeze. B) with the breeze at 1 m/s. C) against the breeze at 1 m/s. D) faster than 1 m/s but less than 2 m/s.

Q: You're at rest in a hammock when a hungry mosquito sees you as lunch, while a 2-m/s breeze is blowing. If the mosquito joins you for lunch, it should first hover over you by flying A) against the breeze at 2 m/s. B) with the breeze at 2 m/s. C) a bit faster than wind speed. D) none of the above

Q: A mosquito flying at 3 m/s encounters a 3-m/s breeze blowing in the opposite direction, which gives it a resulting speed over the ground of A) 0 m/s. B) 3 m/s. C) 4 m/s. D) 6 m/s.

Q: A mosquito flying at 3 m/s encounters a 3-m/s breeze blowing in the same direction, which gives it a resulting speed over the ground of A) 0 m/s. B) 3 m/s. C) 4 m/s. D) 6 m/s.

Q: Nellie runs the length of a 100-yard football field in a time of 20 seconds. Her average running speed is A) 1/2 yard/second. B) 5 yards/second. C) 50 yards/second. D) not enough information

Q: A glance at the speedometer on your vehicle will tell you your A) average speed. B) instantaneous speed. C) overall speed. D) acceleration.

Q: What did Galileo incorporate in his study of motion that Aristotle overlooked? A) the role of distance B) the role of time C) the role of space D) none of the above

Q: The two measurements necessary for calculating average speed are A) acceleration and time. B) velocity and time. C) distance and time. D) distance and acceleration. E) velocity and distance.

Q: Marie pushes horizontally on her desk, but not hard enough to get it moving. The friction force acting on the desk is A) zero. B) equal to the weight of the desk. C) equal and opposite to her push. D) none of the above

Q: A crate is at rest on a horizontal floor, with nobody pushing. The friction force acting on the crate is A) zero. B) equal to the weight of the crate. C) between zero and the weight of the crate. D) none of the above

Q: A 3000-N bear grasping a vertical tree slides down at constant velocity. The friction force between the tree and the bear is A) 30 N. B) 300 N. C) 3000 N. D) more than 3000 N.

Q: When you push a crate across a level floor at constant velocity, friction between the crate and the floor is A) less than your pushing force. B) the same amount as your pushing force. C) more than your pushing force. D) none of the above

Q: The amount of friction that occurs when two blocks slide against each other depends on A) how much they are pressed together. B) the "stickiness" of atoms on their surfaces. C) the kinds of material being pressed. D) all of the above

Q: The resistive force of friction occurs for A) solids. B) liquids. C) gases. D) all of the above

Q: In general, the friction forces between one object and another act A) in the same direction. B) in opposite directions. C) at right angles to each other. D) none of the above

Q: When Marie pushes her desk to the right, friction between the floor and the desk acts toward A) the left. B) the right. C) at right angles to her push. D) none of the above

Q: As you jump up and down on a floor, the support force by the floor experiences A) changes. B) no changes. C) none of the above.

Q: An 800-N woman stands at rest on two bathroom scales so that one scale shows a reading of 500 N. The reading on the other scale is A) 200 N. B) 300 N. C) 400 N. D) 800 N. E) none of the above

Q: An 800-N man stands at rest with his weight evenly distributed on two bathroom scales. The reading on each scale is A) 200 N. B) 400 N. C) 800 N. D) 1600 N. E) none of the above

Q: When Lillian hangs from a pair of gym rings, the upward support forces by the rings will always A) each be half her weight. B) each be equal to her weight. C) add up to equal her weight. D) add up to more than her weight.

Q: When you stand at rest on a pair of bathroom scales, the readings on the scales will always A) each be half your weight. B) each equal your weight. C) add to equal your weight. D) add up to more than your weight.

Q: An empty jug of weight W is at rest on a table. When water of weight w is poured into it, the amount of support force supplied by the table is A) W. B) W + w. C) W - w. D) none of the above

Q: Daisy weighs 120 N and carries Trixie who weighs 40 N on her back. The support force on Daisy's feet is A) 40 N. B) 120 N. C) 160 N. D) more than 160 N.

Q: Joshua stands on a floor that supports him. When Sydney rides piggy-back on Joshua, the support force by the floor beneath Joshua A) decreases. B) remains constant. C) increases.

Q: The support force on a 10-N book that rests on a horizontal surface is A) less than 10 N. B) 10 N. C) greater than 10 N. D) dependent on whether the book lies flat or stands upright.

Q: A parachutist falling at constant velocity is in a state of A) dynamic equilibrium. B) non-dynamic equilibrium. C) being in and out of dynamic equilibrium. D) none of the above

Q: When a crate slides down an incline at a constant velocity it is A) in dynamic equilibrium. B) not in dynamic equilibrium. C) in a state of being in and out of dynamic equilibrium. D) none of the above

Q: A bucket of cement is raised by a rope at constant speed at a construction site. Compared with the force of gravity on the bucket, the upward force supplied by the rope is A) greater. B) equal. C) less.

Q: The force of friction on a sliding object is 50 N. The applied force needed to maintain a constant velocity is A) more than 50 N. B) less than 50 N. C) 50 N.

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 nonzero velocity. C) in mechanical equilibrium. D) all of the above E) none of the above

Q: Burl and Paul have a total weight of 1300 N. The tensions in the ropes that support the scaffold they stand on add to 1700 N. The weight of the scaffold itself must be A) 400 N. B) 500 N. C) 600 N. D) 800 N.

Q: If Burl carried Paul piggy-back while standing in the middle of a scaffold, the tensions in the two supporting ropes would A) cancel to zero. B) be equal. C) be unequal. D) more easily support Burl and Paul.

Q: Burl and Paul on a sign-painting scaffold are in equilibrium, which means that the net upward supporting force of the vertical ropes is A) equal to their weights. B) greater than their weights. C) equal and opposite to the combined weights of Burl, Paul, and the scaffold. D) none of the above

Q: When sign painters Burl and Paul stand on opposite ends of a scaffold, the tensions in each of the two supporting ropes A) are equal. B) depend on the relative weights of Burl and Paul. C) combine to equal zero. D) none of the above

Q: When a 10-N object is suspended at rest by two equally-taut vertical strands of rope, the tension in each strand is A) less than 5 N. B) 5 N. C) more than 5 N. D) 10 N.

Q: The equilibrium rule states that the vector sum of all forces acting on a A) body at rest is zero. B) body in uniform motion is zero. C) non-accelerating body is zero. D) all of the above

Q: Whenever the net force on an object is zero, its acceleration A) may be zero. B) is zero. C) and velocity are the same. D) none of the above

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

Q: The equilibrium rule ΣF = 0 applies to A) objects or systems at rest. B) objects or systems in uniform motion in a straight line. C) both of the above D) neither of the above

Q: Given that two forces of 10 N and 15 N act horizontally on an object, the net force must A) be 5 N. B) be 25 N. C) be either 5 N or 25 N. D) lie between 0 N and 25 N.

Q: A 10-N falling object encounters 10 N of air resistance. The net force on it is A) 0 N. B) 4 N. C) 6 N. D) 10 N.

Q: A 10-N falling object encounters 4 N of air resistance. The net force on it is A) 0 N. B) 4 N. C) 6 N. D) 10 N.

Q: A 50-N object falling in air experiences 30 N of air resistance. The net force on the falling object is A) 0 N. B) 20 N. C) 50 N. D) 80 N.

Q: An object is pulled with three forces: one at 20 N to the right, another at 40 N to the right, and the third at 30 N to the left. The net force is A) 60 N to the right. B) 60 N to the left. C) 30 N to the left. D) none of the above

Q: An object is pulled with two forces, 10 N northward and 15 N southward. The direction of the net force is to the A) north. B) south. C) east. D) west. E) none of the above

Q: An object is pulled with two forces, 10 N northward and 15 N southward. The magnitude of the net force is A) 0 N. B) 5 N. C) 10 N. D) 15 N. E) none of the above

Q: When a 10-kg block is simultaneously pushed toward the east with 20 N and toward the west with 15 N, the combination of these forces on the block is A) 5 N west. B) 5 N east. C) 35 N east. D) 35 N west.

Q: A girl pushes a cart to the left with a 100-N force. At the same time a boy pushes it to the right with a 50-N force. The net force exerted on the cart is A) 50 N to the left. B) 50 N to the right. C) 100 N to the left. D) 100 N to the right.

Q: The net force on an object is A) most often its weight. B) the combination of all forces acting on it. C) the force of friction acting on it.