Homework 1

Question 1

How is a Joule dened in terms of other units?

Answer 1

W * s

(Watts times seconds) This is derived from Power (Watts) = J/s

Question 2

If a laser delivers 30 W of power to a target over 2 seconds, how much energy does it deliver to the target?

Answer 2

60 Joules

(use equation Power = J/s)

(use equation Power = J/s)

Question 3

How is a Watt defined in terms of other units?

Answer 3

J/s

Question 4

The human body produces about 100 W of heat energy per time. How much heat energy does the human body emit in an hour? Recall that an hour has 3600 seconds.

Answer 4

360 kJ

Question 5

If a lightbulb produces 100 J of heat and light energy while on for 10 seconds, how much electrical power does the lightbulb consume?

Answer 5

10 W

Question 6

What was James Watt’s primary contribution?

Answer 6

Making the steam engine much more efficient

Question 7

What is the unit for energy?

Answer 7

Joule

Question 8

Who was credited with starting the industrial revolution with their invention?

Answer 8

James Watt

Question 9

Which of the following was responsible for the industrial revolution?
A. James Watt
B. Scientific Revolution
C. Abundant coal
D. All of the above

Answer 9

D.

Question 10

What is the unit for power?

Answer 10

Watt

Question 11

Who discovered that mechanical work gets converted to heat, thereby establishing the law of conservation of energy?

Answer 11

James Joule

Question 12

By what process does air that is in contact with the Earth’s surface get heat?

Answer 12

Conduction

Question 13

When a mass exchanges energy with a faraway mass by sending photons to it, what do we call this?

Answer 13

Radiation

Question 14

When energy moves from one place to another because a mass carries that energy there, what do we call this?

Answer 14

Convection

Question 15

Which of the following is an example of conduction?
A. warm hands by the fireplace
B. hot air balloon rises
C. burn hand on hot pan
D. the Sun heating the Earth

Answer 15

C.

Question 16

Which of the following is an example of radiation?
A. feeling cold with hand on frosty window
B. burn hand on hot pan
C. hot air balloon rises
D. Warm hands by the fireplace

Answer 16

D.

Question 17

Where does convection move energy into, out of, or within the Earth?
A. within the atmosphere
B. from the surface to the atmosphere
C. all of the other answers
D. from the Sun to the Earth
E. from the Earth to space

Answer 17

A.

Question 18

Which of the following is an example of convection?
A. the Sun heating the Earth
B. hot air balloon rises
C. burn hand on hot pan
D. warm hands by the fireplace

Answer 18

B.

Question 19

Where does conduction move energy into, out of, or within the Earth?
A. all of the other answers
B. from the Earth to space
C. from the surface to the atmosphere
D. within the atmosphere
E. from the Sun to the Earth

Answer 19

C.

Question 20

By what process does energy from the Sun get to Earth’s surface?

Answer 20

Radiation

Question 21

When a mass exchanges energy with an adjacent mass by jiggling against it, what do we call this?

Answer 21

Conduction

Question 22

By what process does a blob of hot air move its heat from Earth’s surface up into the atmosphere?

Answer 22

Convection

Question 23

Why does a small piece of burning paper float up into the air?

Answer 23

Convection

Question 24

Where does radiation move energy into, out of, or within the Earth?
A. from the surface to the atmosphere
B. within the atmosphere
C. all of the other answers
D. from the Sun to the Earth
E. from the Earth to space

Answer 24

C.