Physics HW 1

The scientific method is most effective in A. gaining, organizing, and applying new knowledge. B. performing experiments. C. making theories. D. discovering new things. E. making hypotheses.

A. gaining, organizing, and applying new knowledge.

1. Hypothesis 2. Scientific Law 3. Scientific Theory 4. Equilibrium 5. Inertia A. The characteristic of an object to resist a change in its motion B. An educated explanation for something in nature, which may not be accepted due to lack of repeated testing C. An explanation of how nature works which fits in with other scientific ideas and discoveries D. A description of what happens in nature, that has been repeatedly verified E. The sum of all forces acting on a non-accelerating object is zero

B D C E A

Scientific equations in a conceptual course are mainly A. recipes for plugging in numerical data. B. guides to thinking about the relationships between concepts. C. for mathematical problem solving. D. unfortunately a confusing way of explaining ideas.

B. guides to thinking about the relationships between concepts.

Science is a body of knowledge that extends back to A. the time of Galileo. B. humankind's beginnings. C. Italy in the 16th century. D. Greece in the 7th century B.C.

B. humankind's beginnings.

1. Energy 2. Impulse 3. Momentum 4. Weightlessness 5. Projectile A. Change in momentum B. Inertia in motion C. State of having no support force D. An object that travels under the influence of gravity E. The ability of an object to do work on another object

E A B C D

The gain in speed each second for a freely-falling object is about Answers: 0 m/s. 5 m/s. 10 m/s. 20 m/s. depends on the initial speed.

Selected Answer: 10 m/s.

A machine puts out 100 W of power for every 1000 W put into it. The efficiency of the machine is Answers: 110%. 10%. 90%. 50%.

Selected Answer: 10%.

When a baseball player hits a ball with a force of 1000 N, the ball exerts a force on the bat of Answers: 1000 N. more than 1000 N. less than 1000 N.

Selected Answer: 1000 N.

A 50 N object falling in air experiences 30 N of air resistance. The net force on the falling object is Answers: 0 N. 50 N. 80 N. 20 N.

Selected Answer: 20 N.

A constant net force on a railroad car produces constant Answers: velocity. acceleration. both of these neither of these

Selected Answer: acceleration.

A motor scooter undergoes acceleration when it Answers: gains speed. decreases speed. changes direction. all of the above

Selected Answer: all of the above

Which has zero acceleration? Answers: an object at rest an object moving at constant velocity an object in mechanical equilibrium all of the above none of the above

Selected Answer: all of the above

Science, art, and religion need not contradict one another because Answers: choosing science means that you can forget about religion and art. all three operate in different domains. choosing religion and art allows you to dismiss science. choosing the correct one allows you can forget the other two.

Selected Answer: all three operate in different domains.

In science, a theory is Answers: an explanation based on a large body of well-tested knowledge. less than a fact. an educated guess. unchangeable.

Selected Answer: an explanation based on a large body of well-tested knowledge.

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 Answers: air resistance on the ball. weight of the ball. ball against the bat. grip of the player's hand against the ball. none of the above

Selected Answer: ball against the bat.

A given net force propels an object along a straight-line path. If the mass were doubled, its acceleration would Answers: stay the same. be half. quadruple. double.

Selected Answer: be half.

A very massive object A and a less massive object B move toward each other under the influence of gravity. Which force, if either, is greater? Answers: the force on A the force on B both forces on each other are the same

Selected Answer: both forces on each other are the same

To steadily (constantly) increase the velocity of something requires a Answers: steadily increasing force. constant net force. decreasing force. none of the above

Selected Answer: constant net force.

The two measurements necessary for calculating average speed are Answers: velocity and time. acceleration and time. distance and time. velocity and distance. distance and acceleration.

Selected Answer: distance and time.

Whereas impulse involves the time that a force acts, work involves the Answers: distance that a force acts. time and distance that a force acts. acceleration that a force produces.

Selected Answer: distance that a force acts.

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

Selected Answer: downward and constant.

When Jean standing on slippery ice catches her leaping dog Daisy, the momentum of both Jean and Daisy after the catch is Answers: equal to their combined momentum before the catch. greater than their combined momentum before the catch. somewhat less than their combined momentum before the catch.

Selected Answer: equal to their combined momentum before the catch.

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 Answers: spiral inward. follow a straight-line path. fall straight downward. continue in a circular path.

Selected Answer: follow a straight-line path.

According to Newton, the greater the masses of interacting objects, the Answers: greater the force between them by the square of the masses. greater the gravitational force between them. less the gravitational force between them. greater the force between them by the square of the distance.

Selected Answer: greater the gravitational force between them.

When a bus brakes to a stop, its kinetic energy transforms to Answers: stopping energy. potential energy. heat. energy of motion. energy of rest.

Selected Answer: heat.

In science, an educated guess is a Answers: hypothesis. theory. both

Selected Answer: hypothesis.

The change in momentum of an object is equal to the Answers: force acting on it. change in its velocity. object's mass times the force acting on it. impulse that acts on it. all of the above

Selected Answer: impulse that acts on it.

Two objects move toward each other due to gravity. As the objects get closer and closer, the force between them Answers: increases. remains constant. decreases.

Selected Answer: increases.

Whenever the net force on an object is zero, its acceleration Answers: may be zero. is zero. and velocity are the same. none of the above

Selected Answer: is zero.

An object may have potential energy because of its ______, and an object that has kinetic energy must be ______. Answers: location; moving momentum; mass motionlessness; falling. speed; at rest

Selected Answer: location; moving

Aristotle believed that natural laws could be understood by _______. In contrast to Aristotle's way of explaining nature, Galileo relied on __________. Answers: logic; experiment experiment; logic mathematics; patterns patterns; mathematics

Selected Answer: logic; experiment

In science, facts Answers: are absolute. are more important than theories. may change. mean very little.

Selected Answer: may change.

Science is concerned mainly with the Answers: spiritual world. natural world. difference between right and wrong. search for eternal truths.

Selected Answer: natural world.

With no air resistance a projectile fired horizontally maintains its horizontal component of velocity because Answers: no forces act on it. no horizontal forces act on it. of no initial vertical component of velocity. all of the above none of the above

Selected Answer: no horizontal forces act on it.

According to Galileo, inertia is a Answers: special kind of force. property of all matter. force like any other force. concept opposite to force.

Selected Answer: property of all matter.

The source of Earth's internal energy involves Answers: kinetic energy. the Sun. potential energy. radioactivity.

Selected Answer: radioactivity.

As a bowling ball that rolls off the edge of a table falls, its horizontal component of motion Answers: decreases. increases. remains constant.

Selected Answer: remains constant.

Which of these is a valid scientific hypothesis (that is testable and could be proved wrong)? Answers: the Moon is made of green cheese matter is filled with undetectable particles there are parts of the universe that will never be found by humans none of the above

Selected Answer: the Moon is made of green cheese

Escape speed for a rocket is greatest from Answers: Earth. the Moon. the Sun. same for each

Selected Answer: the Sun.

Occupants of the International Space Station experience weightlessness due to Answers: the absence of a support force. the absence of Earth gravity at that altitude. no gravity in space. rotation of the station.

Selected Answer: the absence of a support force.

Planets wobble in their orbits due to Answers: the gravitational attraction to other planets. uncertainties in the inverse-square law. elliptical-orbit quirks. all of the above none of the above

Selected Answer: the gravitational attraction to other planets.

The pulling of a person's body toward Earth is called weight. The reaction to this force is Answers: the person's body pushing against Earth's surface. Earth's surface pushing against the person's body. the person's body pulling on Earth. none of the above

Selected Answer: the person's body pulling on Earth.

When you push a crate across a level floor at constant velocity to the right, friction between the crate and the floor is Answers: more than your pushing force and to the right the same amount as your pushing force and to the right less than your pushing force and to the left the same amount as your pushing force and to the left

Selected Answer: the same amount as your pushing force and to the left

Compared with the mass of an apple on Earth, the mass of the same apple on the Moon is ____, while the weight of the apple on the Moon is ____ than what it weighs on Earth. Answers: the same; more less; more the same; less more; less

Selected Answer: the same; less

A ball rolling down an incline has its maximum potential energy at ______, and its maximum kinetic energy at ________. Answers: the bottom; the top half-way down; a quarter of the way down the top; the bottom a quarter of the way down; half-way down

Selected Answer: the top; the bottom

Planets would crash into the Sun if it weren't for Answers: the inverse-square law. the fact that they are beyond the main gravitation of the Sun. their vast distances from the Sun. their tangential velocities. their relatively small masses.

Selected Answer: their tangential velocities.

To catch a fast-moving softball with your bare hand, you extend your hand forward just before the catch and then let the ball ride backward with your hand. Doing this reduces the catching force because the Answers: relative velocity is less. time of the catch is decreased. time of catch is increased. relative velocity is more.

Selected Answer: time of catch is increased.

Inside a freely-falling elevator your Answers: acceleration is zero. weight is zero. gravitational interaction with Earth is zero. all the above

Selected Answer: weight is zero.

An object in motion tends to remain in motion Answers: only when an external force acts on it. without the need of a force. because of a force within the object.

Selected Answer: without the need of a force.

Power is defined as the Answers: work done divided by the time to do the work. work done multiplied by the time to do the work. force exerted divided by the time of exertion. force exerted multiplied by the distance moved

Selected Answer: work done divided by the time to do the work.

The force required to maintain an object at a constant velocity in free space is equal to Answers: the force required to stop it. zero. the mass of the object. the weight of the object.

Selected Answer: zero.

A hypothesis that is scientific must have a test for proving it Answers: right. wrong. either.

wrong