Deck 3: Laws of Motion

Question 1

Which of the following is true about a comet that is on an elliptical orbit around the Sun?

A) The comet's speed is greatest when it is farthest from the Sun.
B) The comet's speed is greatest when it is nearest the Sun.
C) This comet's speed is zero.
D) The comet's speed is constant because its mass and the Sun's mass stay approximately the same.

Answer 1

The comet's speed is greatest when it is nearest the Sun.

Question 2

The centrifugal force experienced by a body in circular motion is a reaction to:

A) the force of gravity.
B) the body's weight.
C) the force that causes the motion to be circular.
D) the contact forces between the molecules of the material.

Answer 2

the force that causes the motion to be circular.

Question 3

How are mass and inertia related?

A) More massive objects contain more Inertia.
B) Less massive objects contain more inertia.
C) Inertia and mass are unrelated.
D) Only masses in motion contain intertia.

Answer 3

More massive objects contain more Inertia.

Question 4

If the distance between Earth and the Sun were cut in half,the gravitational force between these two objects would:

A) decrease by 4.
B) decrease by 2.
C) increase by 2.
D) increase by 4.

Question 5

In the figure below,if the acceleration of the container is 2 m/s²,with what force did the woman push?

A) 50 N
B) 100 N
C) 150 N
D) 200 N

Question 6

In which of the following situations would the object be experiencing an unbalanced force?

A) a truck at rest
B) a car moving at constant speed turning a corner
C) a rocket moving at a constant speed straight up away from Earth
D) a car moving at a constant speed toward the right

Question 7

Which of Newton's laws states that if an unbalanced force acts on an object,then the object's motion changes?

A) Newton's first law
B) Newton's second law
C) Newton's third law
D) Newton's law of gravitation

Question 8

Which scientist ended up under house arrest because of his support of the heliocentric model?

A) Galileo Galilei
B) Isaac Newton
C) Johannes Kepler
D) Tycho Brahe

Question 9

The natural tendency of an object to resist changes in motion is called:

A) inertia.
B) weight.
C) acceleration.
D) mass.

Question 10

In the figure below,if the woman pushes with a force of 50 N,what will be the acceleration of the container?

A) 0.5 m/s2
B) 0.75 m/s2
C) 1 m/s2
D) 2 m/s2

Question 11

Which observations made by Galileo are inconsistent with the geocentric model of astronomy?

A) craters on the Moon
B) orbits of Jupiter's moons and phases of Venus
C) retrograde motion of Mars
D) sunspots

Question 12

What do the Copernican and Ptolemaic models have in common?

A) elliptical orbits
B) Sun as center of the universe
C) circular orbits
D) Earth as center of universe

Question 13

If an object is moving in a circular orbit at a constant speed,which of the following is FALSE?

A) Its acceleration is not zero.
B) Its acceleration is zero.
C) Its velocity is not zero.
D) There is an unbalanced force acting on it.

Question 14

An empirical science is one that is based on:

A) assumptions.
B) calculus.
C) computer models.
D) observed data.

Question 15

Newton's first law states that objects in motion:

A) eventually come to rest.
B) experience an unbalanced force.
C) experience a nonzero acceleration.
D) stay in motion unless acted upon by an external force.

Question 16

If a 100-kg astronaut pushes on a 5,000-kg satellite and the satellite experiences an acceleration of 0.1 m/s²,what is the acceleration experienced by the astronaut in the opposite direction?

A) 5 m/s2
B) 10 m/s2
C) 50 m/s2
D) 0.1 m/s2

Question 17

In a spaceship orbiting Earth,two astronauts want to measure the mass of a mouse.How can they easily do it if they are in constant free fall?

A) Place the mouse on a spring-loaded scale and weigh it.
B) Measure the gravitational attraction between the mouse and a steel ball of known mass.
C) Drop the mouse from the top of the spaceship to its bottom.
D) Push on the mouse with a known force and measure its acceleration.

Question 18

Which of the following did NOT require the use of a telescope to observe?

A) spots on the Sun
B) retrograde motion of the planets
C) phases of Venus
D) Jupiter's moons

Question 19

What is your acceleration if you go from 0 to 60 mph in 4 seconds?

A) 60 mph/s
B) 30 mph/s
C) 15 mph/s
D) 8.5 mph/s

Question 20

You apply a force of 10 N to a grocery cart in order to get an acceleration of 0.5 m/s².If you apply a force of 20 N to the same grocery cart,its acceleration will be:

A) 10 m/s2.
B) 1 m/s2.
C) 0.5 m/s2.
D) 0.25 m/s2.

Question 21

What force holds planets in their orbits?

A) air resistance
B) friction
C) electromagnetic
D) gravity

Question 22

In the figure below,the force of gravity is drawn in the picture.This represents Earth's gravity pulling down on the man.According to Newton's third law,what is the other half of this pair of forces?

A) the floor pushing up on the man
B) the man pushing on the floor
C) the man's gravity pulling up on Earth
D) the floor pushing backward on the man

Question 23

How much would the force of gravity at the surface of the Earth differ if Earth's volume were increased 125 times while its mass was increased 25 times?

A) 25 times less
B) no difference
C) 25 times larger
D) 125 times less

Question 24

How much would the force of Earth's gravity at its surface differ if the Earth's volume were increased 125 times while its mass was increased 25 times?

A) 25 times less
B) 25 times larger
C) no difference
D) 125 times less

Question 25

Once a satellite's velocity at closest approach equals or exceeds the ________ velocity,it is in an unbound orbit.

A) tangential
B) linear
C) circular
D) escape

Question 26

Suppose you are suddenly transported to a planet with one-fourth the mass of Earth but the same radius as Earth.Your weight would ________ by a factor of ________.

A) increase; 4
B) increase; 16
C) decrease; 4
D) decrease; 16

Question 27

List at least three discoveries Galileo made by making astronomical observations through a telescope.

Question 28

Suppose you are suddenly transported to a planet with one-fourth the radius of Earth but the same mass as Earth.Your weight would ________ by a factor of ________.

A) increase; 4
B) increase; 16
C) decrease; 4
D) decrease; 16

Question 29

Two rocks (call them S and T)are a distance of 50 km from one another.Rock S has 20 times the mass of rock T.Which rock will move faster if the only force involved is their mutual gravitational attraction?

A) rock S
B) Both rocks will move at the same speed.
C) rock T
D) Not enough information is available to answer.

Question 30

What two pieces of information do we need to know about Earth in order to calculate the mass of the Sun?

A) The semimajor axis of Earth's orbit and the mass of Earth.
B) The semimajor axis of Earth's orbit and Earth's orbital period.
C) The radius of Earth and Earth's orbital period.
D) The radius of Earth and the mass of Earth.

Question 31

The force of gravity between Earth and the Sun is ________ the force of gravity between Earth and the Moon.For reference,the average distance between Earth and the Moon is 0.003 AU,the mass of the Moon is 7 × 10²² kg,and the mass of the Sun is 2 × 10³⁰ kg.

A) 86,000 times larger than
B) 260 times larger than
C) 140 times smaller than
D) 6,400 times smaller than

Question 32

What type of orbit results when a satellite has a velocity greater than the escape velocity?

A) unbound
B) bound
C) circular
D) linear

Question 33

Your weight is directly proportional to your:

A) height.
B) age.
C) mass.
D) altitude.

Question 34

Astronauts orbiting Earth in a spacecraft feel weightless in space because:

A) they are farther away from Earth.
B) they eat less food while in orbit.
C) the added gravitational pull of the Moon balances Earth's gravitational pull.
D) they are in constant free fall around Earth.

Question 35

If your weight on Earth was 500 N,what would your weight be on the Moon?

A) 83 N
B) 125 N
C) 250 N
D) 500 N

Question 36

The force of gravity that an object has is directly related to its:

A) inertia.
B) size.
C) mass.
D) density.

Question 37

In the absence of air friction,a 0.001-kg piece of paper and a 0.1-kg notebook are dropped from the same height and allowed to fall to the ground.How do their accelerations compare?

A) The accelerations are the same.
B) The notebook's acceleration is 100 times faster than the paper's acceleration.
C) The notebook's acceleration is 1,000 times faster than the paper's acceleration.
D) The paper's acceleration is 100 times faster than the notebook's acceleration.

Question 38

If you weighed 150 lb on Earth,what would you weigh on Mars? For reference,Mars has a mass that is 0.1 times Earth's mass,and Mars has a radius that is 0.5 times Earth's radius.

A) 30 lb
B) 110 lb
C) 76 lb
D) 60 lb

Question 39

Which of the following properties of an astronaut changes when he or she is standing on the Moon,relative to when the astronaut is standing on Earth?

A) weight
B) mass
C) inertia
D) all of the above

Question 40

What is the weight of a 100 kg mass on the moon?

A) 9.8 Newtons
B) 980 Newtons
C) 100 Newtons
D) 163 Newtons

Question 41

How much stronger is the gravitational force of the Sun on Earth compared to the gravitational force of the Sun on Pluto? Note that Pluto's semimajor axis is 40 AU,and its mass is 0.002 times the mass of Earth.

Question 42

An analogy of orbital motion is the twirling of a ball connected by a string.What is the action-reaction force pair described by Newton's third law?

Question 43

What is required to change an object's motion?

Question 44

Examine the figure below.If the acceleration of the container is 2 m/s²,with what force did the woman push?

Question 45

The figure below shows Newton's cannonball thought experiment.At the three locations of the cannonball shown,draw and label arrows representing the circular velocity and acceleration.

Question 46

Name the two ways in which an object's motion (meaning its velocity)can experience a nonzero acceleration.

Question 47

What acceleration would result from a 5-N force acting on a 3-kg object? (A Newton [N] has units of kg m/s².)

Question 48

Explain the difference between being weightless and being in free fall.

Question 49

Is there a difference in your weight between when you are on top of a mountain at 1,000 meters above sea level compared to when you are sitting in a classroom at 10 meters above sea level?

Question 50

An object in a circular orbit is in a perpetual state of free fall,i.e.,accelerating toward Earth but never reaching it.Explain.

Question 51

In a period of 3 months,a planet travels 30,000 km with an average speed of 10.5 km/s.Some time later,the same planet travels 65,000 km in 3 months.How fast is the planet traveling at this later time? During which period is the planet closer to the Sun?

Question 52

What information would you need to obtain about one of the moons of the planet Jupiter in order to measure the mass of Jupiter?

Question 53

If a 100-kg asteroid collides with Earth,causing the asteroid to decelerate in 1 second from 1,000 m/s to 0 m/s,what acceleration will Earth experience according to Newton's third law? (Earth has a mass of approximately 6 × 10²⁴ kg.)

Question 54

Examine the figure below.If the woman pushes with a force of 200 N,what is the acceleration of the container?

Question 55

If every action of a force is met by an equal but opposite force,why does anything accelerate?

Question 56

Astronauts feel "weightless" on the Moon.Using Newton's universal law of gravitation,explain why astronauts experience this feeling.

Question 57

According to Newton's third law,forces come in pairs.Two forces in the figure below are labeled.Label the other half of the pairs.

Question 58

Given a constant acceleration from rest,how is the increase in speed computed?

Question 59

In the figure below,draw an arrow representing the direction of the acceleration in each case.If the acceleration is zero,write zero.