Chapter 4 Part 1

The ultimate source of energy that powers the Sun is

mass energy of hydrogen fusing into helium.

Newton's second law of motion tells us that the net force applied to an object equals its

mass times acceleration

Momentum is defined as

mass times velocity.

Compared to their values on Earth, on another planet your

mass would be the same but your weight would be different.

What quantities does angular momentum depend upon?

mass, velocity, and radius

Nuclear fusion in stars converts some of the____energy of hydrogen nuclei into light and heat.

mass-

Which of the following is not a conserved quantity?

radiation

The light from Polaris travels through space in the form of____energy.

radiative

What does temperature measure?

the average kinetic energy of particles in a substance

When you are standing on a scale in an elevator, what exactly does the scale measure?

the force you exert on the scale

In the formula E = mc2, what does E represent?

the mass-energy, or potential energy stored in an object's mass

Due to its much higher density, water heated to 80 degrees (Celsius) contains more____energy than air at the same temperature.

thermal

As long as an object is not gaining or losing mass, a net force on the object will cause a change in

velocity.

In which of the following cases would you feel weightless?

while falling from a roof

If your mass is 60 kg on Earth, what would your mass be on the Moon?

60kg.

Part D: Which of the following statements correctly state general principles of motion? (Assume that the moving object's mass is not changing.)

-An object that is accelerating is also undergoing a change in momentum. -Accelerated motion includes any motion involving a change in speed, change in direction, or both. -An object that is accelerating is also being acted upon by a (nonzero) net force.

Absolute zero is

0° Kelvin

The acceleration of gravity on Earth is approximately 10 m/s2 (more precisely, 9.8 m/s2). If you drop a rock from a tall building, about how fast will it be falling after 3 seconds?

30 m/s

Standing on the surface of the Earth you drop a rock down a well and it falls for 5 seconds before hitting the bottom. How fast is it moving when it hits the bottom of the well? Neglect air resistance.

50 m/s

Of the temperature ranges below, which range represents the smallest range of actual temperature?

50-100° Fahrenheit

Choose the correct description of an object that is accelerating?

A car going around a circular track at a steady 100 miles per hour.

Considering Einstein's famous equation, E = mc2, which of the following statements is true?

A small amount of mass can be turned into a large amount of energy.

a planet moves faster in the part of its orbit nearer the Sun and slower when farther from the Sun, sweeping out equal areas in equal times.

Kepler's Second Law

explains why Earth's orbital speed varies over the course of each year.

Kepler's Second Law

Part A: Drag each statement into the correct bin based on whether it describes motion that involves acceleration or motion at constant velocity. Note: For the motions that are on Earth (e.g., car, ball, elevator), ignore any effects of Earth's rotation or orbit.

Acceleration - a car is speeding up after being stopped, a ball is in free fall after being dropped from a high window, a car is slowing down for a stop sign, a planet is orbiting the sun in an elliptical orbit, a car is holding a steady speed around a curve, a planet is orbiting the sun in a circular orbit Constant Velocity - an elevator is going upward at constant speed, a car is driving 100 km/hr on a straight road, a spaceship is coasting without engine power in deep space

explains why Earth orbits the Sun at a faster average speed than Mars.

Kepler's Third Law

more distant planets orbit the Sun at slower average speeds, obeying the precise mathematical relationship p2 =a3.

Kepler's Third Law

Part B: Drag each statement into the correct bin based on whether it describes motion in which the object's momentum is changing. Note: For the motions that are on Earth (e.g., car, ball, elevator), ignore any effects of Earth's rotation or orbit.

Change in Momentum - A planet is orbiting the Sun in an elliptical orbit, a car is speeding up after being stopped, a car holding a steady speed around a curve, a ball is in freefall after being dropped from a high window, a planet is orbiting the sun in a circular orbit, a car is slowing down for a stop sign. Constant Momentum - a car is driving 100 km/hr on a straight road, a spaceship is coasting without engine power in deep space, an elevator is going upward at constant speed.

Consider the statement "There's no gravity in space." This statement is:

Completely false.

explains why Earth's distance from the Sun varies over the course of each year.

Kepler's First Law

the orbit of each planet about the Sun is an ellipse with the Sun at one focus.

Kepler's First Law

Each of the following items states a temperature, but does not tell you whether the temperature is measured on the Fahrenheit, Celsius, or Kelvin scale. Match the items to the appropriate temperature scale.

F - A hot summer day might be 100, Ice cream is stored in freezers at 26 C - Water freezes into ice at 0, a typical room temperature is 24, liquid water boils at 100 K - Water boils into gas phase at 373.15, the coldest possible temperature is 0

Speed and velocity are the same thing.

False

When energy is converted from one form to another, a tiny amount is inevitably lost.

False

How does the Space Shuttle take off?

Hot gas shoots out from the rocket and, by conservation of momentum, the shuttle moves in the opposite direction.

Where does the energy come from that your body uses to keep you alive?

It comes from the foods you eat.

What would happen if the Space Shuttle were launched with a speed greater than Earth's escape velocity?

It would travel away from Earth into the solar system.

Part C: Drag each statement into the correct bin based on whether it describes motion in which the object's momentum is changing. Note: For the motions that are on Earth (e.g., car, ball, elevator), ignore any effects of Earth's rotation or orbit.

Net Force (nonzero) - a planet is orbiting the Sun in an elliptical orbit, a car is slowing down for a stop sign, a ball is in freefall after being dropped from a high window, a car is speeding up after being stopped, a car is holding a steady speed around a curve, a planet is orbiting the Sun in a circular orbit. No Net Force - an elevator is going upward at constant speed, a car is driving 100 km/hr on a straight road, a spaceship is coasting without engine power in deep space.

an object moves at constant velocity if there is no net force acting upon it.

Newton's First Law

explains why a spaceship with no forces acting on it will continue moving even if it has no fuel.

Newton's First Law

explains why applying a force to a baseball with your arm can cause the baseball to accelerate from rest to the speed at which it leaves your hand.

Newton's Second Law

force = mass x acceleration

Newton's Second Law

for any force, there is an equal and opposite reaction force.

Newton's Third Law

tells us that, when your are standing, the ground is pushing up on you with a force that precisely balances the downward force of your weight.

Newton's Third Law

The fact that the Voyager spacecraft continues to travel out of the solar system, even though its rockets have no fuel, is an example of

Newton's first law of motion.

Which of the following examples describes a situation where a car is experiencing a net force?

The car is making a gradual turn.

In Part A, you found that your weight will be greater than normal when the elevator is moving upward with increasing speed. For which of the following other motions would your weight also be greater than your normal weight?

The elevator moves downward while slowing in speed.

When a rock is held above the ground, we say it has some potential energy. When we let it go, it falls and we say the potential energy is converted to kinetic energy. Finally, the rock hits the ground. What has happened to the energy?

The energy goes to producing sound and to heating the ground, rock, and surrounding air.

Which of the following statements correctly describes the law of conservation of energy?

The total quantity of energy in the universe never changes.

If you are driving at 30 miles per hour and increase your speed to 60 miles per hour, you quadruple your kinetic energy.

True

Which of the following scenarios correctly demonstrates the transformation of mass into energy as given by Einstein's equation, E = mc2?

When hydrogen is fused into helium, whether in the Sun or in a nuclear bomb, the mass difference is turned into energy.

Suppose you are in an elevator car when the elevator cable breaks. Which of the following correctly describes what happens and why.

You float weightlessly within the elevator car because you and the elevator both begin to accelerate downward at the same rate.

Suppose you lived on the Moon. Which of the following would be true?

Your weight would be less than your weight on Earth, but your mass would be the same as it is on Earth.

Which object has the most kinetic energy?

a 2-ton truck moving 90 km/hr

An apple contains____energy that your body can convert into other forms energy.

chemical potential

Gasoline is useful in cars because it has

chemical potential energy

A skater can spin faster by pulling her arms closer to her body or spin slower by spreading her arms out from her body. This is due to

conservation of angular momentum.

Suppose an object is moving in a straight line at 50 miles/hr. According to Newton's first law of motion, the object will

continue to move in the same way until it is acted upon by a force.

If an object's velocity is doubled, its momentum is

doubled.

Which of the following is an example in which you are traveling at constant speed but not at constant velocity?

driving around in a circle at exactly 100 km/hr

Radiative energy is

energy carried by light.

An asteroid that is moving farther from the Sun is gaining____energy.

gravitational potential

Suppose you are in an elevator. As the elevator starts upward, its speed will increase. During this time when the elevator is moving upward with increasing speed, your weight will be

greater than your normal weight at rest

The amount of gravitational potential energy released as an object falls depends on

its mass and the distance it falls, as well as the rate of gravitational acceleration.

Rapidly moving comets have more____energy than slowly moving ones

kinetic

Suppose you are in an elevator that is moving upward. As the elevator nears the floor at which you will get off, its speed slows down. During this time when the elevator is moving upward with decreasing speed, your weight will be

less than your normal weight at rest