PHY 2020 Homework Module 1

Two billiard balls having the same mass and speed roll toward each other. What is their combined momentum after they meet? A) 0 B) half the sum of their original momentums C) twice the sum of their original momentums D) impossible to determine without additional information

A) 0

A ball is thrown upwards from the surface of the earth at the speed 10m/s. It returns to the same position. How long does it stay in the air (neglect the air resistance)? A) 2s B) 4s C) 5s D) 0s

A) 2s

A 4 kg ball has a momentum of 12 kg m/s. What is the ball's speed? A) 3 m/s B) 4 m/s C) 12 m/s D) 48 m/s E) none of these

A) 3 m/s

In science, a theory is ------- A) a synthesis of a large body of well-tested knowledge. B) less than a fact. C) unchangeable. D) an educated guess.

A) a synthesis of a large body of well-tested knowledge. B) less than a fact.

The mass of a pet turtle that weighs 10 N is A) about 1 kg. B) about 10 kg. C) about 100 kg. D) about 1000 kg. E) none of these

A) about 1 kg.

The famous Leaning Tower of Pisa doesn't topple over because its center of gravity is A) above a place of support. B) relatively low for such a tall building. C) stabilized by its structure. D) displaced from its center. E) in the same place as its center of mass.

A) above a place of support.

If the Earth had two identical moons in one circular orbit, and the moons were as far apart in that orbit as they could be, the center of gravity of the Earth-moons system would be A) at the center of the Earth. B) inside the Earth, but off center. C) outside the Earth, but within the orbital path of the moons. D) outside the Earth, but beyond the orbital path of the moons.

A) at the center of the Earth.

The newton (N) is a unit of A) force. B) mass. C) density. D) inertia.

A) force.

An Earth satellite is simply a projectile A) freely falling around the Earth. B) floating motionless in space near the Earth. C) approaching the Earth from outer space.

A) freely falling around the Earth.

A heavy truck and a small car rolling down a hill at the same speed are forced to stop in the same amount of time. Compared to the force that stops the car, the force needed to stop the truck is A) greater. B) smaller. C) the same.

A) greater.

When a twirling ice skater brings her arms inward, her rotational speed A) increases. B) decreases. C) remains the same.

A) increases.

Two tennis balls fall through the air from a tall building. One of them is filled with lead pellets. In presence of air-resistance, the ball to reach the ground first is the ---- A) lead-filled ball. B) regular ball. C) same for both

A) lead-filled ball.

An object that has kinetic energy must be A) moving. B) falling. C) at an elevated position. D) at rest. E) none of these

A) moving.

An Earth satellite is in an elliptical orbit. The satellite travels fastest when it is A) nearest the Earth. B) farthest from the Earth. C) It travels at constant speed everywhere in orbit.

A) nearest the Earth.

If you push for a half hour or a whole hour against a stationary wall A) no work on the wall is done in either case. B) half as much work is done during the half hour. C) twice as much work is done during the half hour. D) it is impossible to determine how much work is done.

A) no work on the wall is done in either case.

If more horizontal force is applied to a sliding object than is needed to maintain a constant velocity A) the object accelerates in the direction of the applied force. B) the object accelerates opposite the direction of the applied force. C) the friction force increases. D) two of the above E) none of the above

A) the object accelerates in the direction of the applied force.

While an object near the Earth's surface is in free fall, its A) velocity increases. B) acceleration increases. C) mass increases. D) velocity decreases.

A) velocity increases.

Scientific hypothesis may turn out to be right or it may turn out to be wrong. If it is a valid hypothesis, there must be a test for proving it---- A) wrong. B) right.

A) wrong

Which is the following is not a vector quantity? A. Mass B. Weight C. Force D. Acceleration E. None of these

A. Mass

An object is dropped and freely falls to the ground with an acceleration of 1 g. If it is thrown upward (neglecting air-resistance) at an angle instead, its acceleration will be A) 0 g. B) 1 g downward. C) 1 g upward. D) larger than 1 g. E) none of these

B) 1 g downward.

A 1-kg chunk of putty moving at 1 m/s collides with and sticks to a 5-kg bowling ball initially at rest. The bowling ball and putty then move with a momentum of A) 0 kg m/s. B) 1 kg m/s. C) 2 kg m/s. D) 5 kg m/s. E) more than 5 kg m/s.

B) 1 kg m/s.

An object at rest near the surface of a distant planet starts to fall freely. If the acceleration due to gravity there is twice that of the Earth, its speed one second later would be A) 10 m/s. B) 20 m/s. C) 30 m/s. D) 40 m/s.

B) 20 m/s.

A baseball bat is balanced on a fulcrum. The center of gravity of the bat is located A) closer to the handgrip. B) above the fulcrum. C) insufficient information

B) above the fulcrum.

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) neither of these

B) acceleration.

Inside a freely falling elevator, there would be no A) gravitational force on you. B) apparent weight for you. C) both of these D) none of these

B) apparent weight for you.

Toss a baseball bat into the air and it wobbles about its A) geometrical center. B) center of mass. C) heavier end.

B) center of mass.

If an object moves with constant acceleration, its velocity must A) be constant also. B) change by the same amount each second. C) change by varying amounts depending on its speed. D) always decrease.

B) change by the same amount each second.

If no external forces are acting on a moving object, it will A) continue moving at the same speed. B) continue moving at the same velocity. C) move slower and slower until it finally stops.

B) continue moving at the same velocity.

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) decreases.

A freight train rolls along a track with considerable momentum. If it rolls at the same speed but has twice as much mass, its momentum is A) zero. B) doubled C) quadrupled. D) unchanged.

B) doubled

A popular swinging-balls apparatus consists of an aligned row of identical elastic balls that are suspended by strings so they barely touch each other. When two balls are lifted from one end and released, they strike the row and two balls pop out from the other end. If instead one ball popped out with twice the speed of the two, this would be a violation of conservation of A) momentum. B) energy. C) both of these D) none of these

B) energy.

A player catches a ball. Consider the action force to be the impact of the ball against the player's glove. The reaction to this force is the A) player's grip on the glove. B) force the glove exerts on the ball. C) friction of the ground against the player's shoes. D) muscular effort in the player's arms. E) none of these

B) force the glove exerts on the ball.

According to Newton, the greater the masses of interacting objects, the A) less the gravitational force between them. B) greater the gravitational force between them. C) greater the force between them by the square of the masses.

B) greater the gravitational force between them.

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) none of these

B) has zero acceleration.

A heavy rock and a light rock of the same size are falling through the air from a tall building. The one that encounters the greatest air resistance is the A) light rock. B) heavy rock. C) same for both

B) heavy rock.

A bullet is fired horizontally from a gun. At the same time a similar bullet is dropped from the same height. The fired bullet will (neglect air-resistance) A) hit the ground first B) hit at the same time as the dropped bullet C) hit the ground second D) never hit the ground

B) hit at the same time as the dropped bullet

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) increases.

Whenever the net force on an object is zero, its acceleration A) may be less than zero. B) is zero. C) may be more than zero

B) is zero.

Which has greater kinetic energy, a car traveling at 30 km/hr or a car of half the mass traveling at 60 km/hr? A) the 30 km/hr car B) the 60 km/hr car C) Both have the same kinetic energy. D) More information is needed about the distance traveled.

B) the 60 km/hr car

A block of ice sliding down an incline has its maximum speed at A) the top. B) the bottom. C) halfway down. D) difficult to predict without knowing the slope of the incline E) difficult to predict without knowing the coefficient of friction

B) the bottom.

It is correct to say that impulse is equal to A) momentum. B) the change in momentum it produces. C) the force multiplied by the distance the force acts. D) velocity multiplied by time.

B) the change in momentum it produces.

Your weight is A) equal to your mass. B) the gravitational attraction force between you and the Earth. C) a property of mechanical equilibrium. D) all of these

B) the gravitational attraction force between you and the Earth.

If an object is raised twice as high, its potential energy will be A) half as much B) twice as much. C) four times as much. D) impossible to determine unless the time is given

B) twice as much.

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

B) zero.

An apple at rest weighs 1 N. The net force on the apple when it is in free fall is A) 0 N. B) 0.1 N. C) 1 N. D) 9.8 N. E) none of these

C) 1 N.

The force of friction on a sliding object is 10 N. The applied force needed to maintain a constant velocity is A) more than 10 N. B) less than 10 N. C) 10 N.

C) 10 N.

The weight of a 1-kg mass at the Earth's surface is about A) 1 kg. B) 4.9 N. C) 10 N. D) 100 N. E) none of these

C) 10 N.

Ten seconds after starting from rest, a car is moving at 40 m/s. What is the car's acceleration ? A) 0.25 m/s2 B) 4.0 m/s C) 4.0 m/s2 D) 10 m/s2 E) 40 m/s

C) 4.0 m/s2

A man weighing 1000 N stands at rest on two bathroom scales so that his weight is distributed evenly over both scales. The reading on each scale is A) 200 N. B) 1000 N. C) 500 N. D) none of these

C) 500 N.

A person is attracted toward the center of Earth by a 500-N gravitational force. The Earth is attracted toward the person with a force of A) zero. B) 250 N. C) 500 N. D) 1000 N.

C) 500 N.

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

C) 6 N.

What task requires the most work; lifting a 50-kg sack 2 meters or lifting a 25- kg sack 4 meters? A) the 50-kg sack B) the 25-kg sack C) Both require the same amount of work. D) impossible to determine without knowing the contents of the sack

C) Both require the same amount of work.

Disregarding air resistance, objects fall with constant A) velocity. B) speed. C) acceleration. D) distances each successive second

C) acceleration.

Neglecting friction, a large block of ice and a small block of ice start sliding down an incline together. The heavier block will get to the bottom ------- A) after the light block. B) before the light block. C) at the same time as the light block

C) at the same time as the light block

A rock is thrown upward at 50 degrees with respect to the horizontal. As it rises, neglecting air drag, its vertical component of velocity A) increases. B) remains unchanged. C) decreases.

C) decreases.

According to Newton, doubling the distance between two interacting objects A) divides by 2 the gravitational force between them. B) multiplies by 2 the gravitational force between them. C) divides by 4 the gravitational force between them. D) multiplies by 4 the gravitational force between them.

C) divides by 4 the gravitational force between them.

The acceleration due to gravity acts: A) upward B) depending on the motion of the object C) downward D) toward outer space

C) downward

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. B) more than its weight. C) equal to its weight.

C) equal to its weight.

A player hits a ball with a bat. The action force is the impact of the bat against the ball. The reaction to this force is the A) air resistance on the ball. B) weight of the ball. C) force that the ball exerts on the bat. D) grip of the player's hand against the ball. E) weight of the bat.

C) force that the ball exerts on the bat.

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 these E) none of these

C) in mechanical equilibrium.

A kilogram is a measure of an object's A) weight. B) force. C) mass. D) size.

C) mass.

Two objects have the same size and shape, but one is much heavier than the other. When they are dropped simultaneously from a tower, they reach the ground at the same time, but the heavier one has a greater A) speed. B) acceleration. C) momentum. D) all of these E) none of these

C) momentum.

The reason the moon does not crash into the Earth is that the A) Earth's gravitational field is weak at the moon. B) gravitational pull of other planets keeps the moon up. C) moon has a sufficient tangential speed. D) moon has less mass than the Earth. E) none of these

C) moon has a sufficient tangential speed.

A ring, a cylinder, and a solid sphere begin rolling down a hill together. Given that the rotational inertia of the solid sphere is the least and that of the ring is the most , the one to reach the bottom first is the A) ring B) cylinder. C) sphere. D) They all reach the bottom at the same time. E) Not enough information is given.

C) sphere.

Compared to falling on a stone floor, a wine glass may not break when it falls on a carpeted floor because the A) carpeted floor provides a smaller impulse. B) stopping time is shorter on the carpet. C) stopping time is longer on the carpet. D) carpet provides a smaller impulse and a longer time.

C) stopping time is longer on the carpet.

The center of mass of a human body is located at a point A) that is fixed, but different for different people. B) that is always directly behind the belly button. C) that changes as a person bends over. D) none of these

C) that changes as a person bends over.

A car traveling at 100 km/hr strikes an unfortunate bug and splatters it. The force of impact is A) greater on the bug. B) greater on the car. C) the same for both.

C) the same for both.

A ball is thrown upwards and returns to the same position. Compared with its original speed after release, its speed when it returns is about -- A) twice as much. B) half as much. C) the same. D) four times as much.

C) the same.

A ball is thrown upwards and returns to the same position. Compared with its original speed after release, its speed when it returns is about -------- A) twice as much. B) half as much. C) the same. D) four times as much.

C) the same.

Passengers in a high-flying jumbo jet feel their normal weight in flight, while passengers in the orbiting space shuttle do not. This is because passengers in the space shuttle are A) beyond the main pull of Earth's gravity. B) above the Earth's atmosphere. C) without support forces. D) all of these E) none of these

C) without support forces.

A 5 kg ball has a acceleration of 2 m/s2. The the magnitude of the force responsible for producing this acceleration is A) 3 N B) 4 N C) 10 kg D) 10 N E) none of these

D) 10 N

A TV set is pushed a distance of 2 m with a force of 20 N. How much work is done on the set? A) 2 J B) 10 J C) 20 J D) 40 J E) 800 J

D) 40 J

A rock is thrown straight up from the surface of the Earth. Which one of the following statements describes the energy transformation of the rock as it rises? Neglect air resistance. A) The total energy of the rock increases.! B) The kinetic energy increases and the potential energy decreases.! C) Both the kinetic energy and the potential energy of the rock remain the same.! D) The kinetic energy decreases and the potential energy increases.! E) Both the potential energy and the total energy of the rock increase.

D) The kinetic energy decreases and the potential energy increases.!

An object in mechanical equilibrium is an object A) at rest. B) moving with constant velocity. C) having no acceleration. D) all of these

D) all of these

Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has twice as much ---- A) inertia. B) volume. C) mass. D) all of these E) none of these

D) all of these

According to Kepler's laws, the paths of planets about the sun are A) parabolas. B) circles. C) straight lines. D) ellipses. E) none of these

D) ellipses.

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) quadruples. B) doubles. C) stays the same. D) halves. E) none of these

D) halves.

When an automobile is braked to a stop, its kinetic energy is transformed to A) stopping energy. B) energy of motion. C) energy of rest. D) heat.

D) heat.

In each second of fall, the distance a freely falling object will fall is A) about 5 m. B) about 10 m. C) the same, but not 5 m or 10 m. D) increasing. E) none of these

D) increasing.

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

D) none of the above

An object may have potential energy because of its A) speed. B) acceleration. C) momentum. D) position. E) none of these

D) position.

A ball rolling down an incline has its maximum kinetic energy at A) the top. B) halfway down. C) three-quarters of the way down. D) the bottom.

D) the bottom.

A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. This best demonstrates that A) the milk carton has no acceleration. B) there is an action-reaction pair of forces. C) gravity tends to hold the milk carton secure. D) the milk carton has inertia. E) none of these

D) the milk carton has inertia.

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

E) distance and time.