10.1
One type of energy travels as a wave through matter. It causes particles to vibrate in the same direction that the wave travels. Which type of energy is it?
sound
A bowling ball is rolled down a bowling alley. Which of these actions would increase the kinetic energy?
A. lifting the ball into the air
B. rolling the ball more slowly
C. using a ball with a greater mass
D. rolling the ball a shorter distance
C. using a ball with a greater mass
Cecilia is combing her hair. She notices that her hair and the comb have developed an electric charge. What will happen when she holds the comb near a small, uncharged object?
The uncharged object will stick to the comb.
A light bulb converts electrical energy into what energy?
heat and light
Some materials conduct electric current and other materials prevent the flow of electric current. Which object prevents the flow of electric current?
A. salt water
B. rubber eraser
C. steel frying pan
D. copper water pipe
rubber eraser
John is hungry and eats an apple. Most of the energy he obtains from the apple is what type?
chemical
A person moves a heavy box across the floor. Which answer best describes the type of energy transformation that occurs when the person uses her muscles to push the box across the floor?
a. chemical into kinetic
b. electrical into chemical
c. kinetic into potential
d. potential into chemical
chemical into kinetic
Carlita hangs two balloons from a desk. When they hang normally, they are close together but they do not touch. Carlita rubs both balloons with a wool cloth. What happens when she lets the balloons hang near one another?
They push one another apart.
An electric fan plugs into the wall. When the switch is turned on, a motor in the fan rotates the blades. The spinning blades create a breeze, which can make a room feel cooler. Which series best summarizes the main energy transformation in a fan?
A. light energy - electrical energy
B. electrical energy - heat energy
C. sound energy - energy of motion
D. electrical energy - energy of motion
electrical energy - energy of motion
Some materials conduct electric current and others prevent the flow of electric current. Which of these building materials is an electrical conductor?
A. bolt
B. brick
C. carpet
D. window
bolt
Ginny picks up her backpack from the floor and puts several books in it. She then puts the backpack on her back and walks across the room toward her desk. She sets the backpack down on the floor next to her desk and begins doing her science homework. During which step does the potential energy of the backpack stay the same?
carrying it across the room on her back
Sandra is making a pencil box. She places a nail in the wood and hits the nail with a hammer. The nail moves into the wood. Which type of energy causes the nail to move into the wood?
kinetic energy
Mandy combs her hair with a plastic comb. This causes the comb to become negatively charged. Which of the following would all be attracted to the comb?
a positively charged object and an uncharged object
Daniel is using an electric mixer to mix pancake batter. When he turns the mixer on, the beaters turn quickly. The mixer makes noise and becomes warm. Which three forms of energy is Daniel transforming electrical energy into?
motion, heat, and sound
All electric circuits need certain components in order to work. Which of the following must be part of an electric circuit?
A. copper wires
B. light bulb or buzzer
C. switch or circuit breaker
D. battery or other source of current
battery or other source of current
An object has a type of energy due to the movement of electrons. Which type of energy is it?
electrical
Which type of energy changes take place when the candle burns?
A. Chemical energy changes into thermal energy and light energy.
B. Electrical energy changes into light energy and chemical energy.
C. Kinetic energy changes into potential energy and thermal energy.
D. Potential energy changes into chemical energy and light energy.
A. Chemical energy changes into thermal energy and light energy.
Curtis uses a wool cloth to give a balloon a negative charge. What will happen when he holds the balloon near the wall, and why?
The balloon will stick to the wall because a negatively charged object is attracted to an uncharged object.
On a warm day, Andrea switched on the ceiling fan in her living room. Which energy transformation causes the blades of the fan to turn?
electrical energy into energy of motion
When you walk into a dark room, you flip a switch on the wall and the lights come on. What is the purpose of the wall switch?
It closes a circuit so that electric current can flow through the lights.
A roller coaster is moving along a track.
Describe how the coaster’s energy changes as it moves down the hill.
The potential energy of the coaster decreases, but the kinetic energy of the coaster increases.
Students’ answers should include:
• that the potential energy decreases as the height of the coaster above the ground decreases
• that the kinetic energy of the coaster increases as the speed of the coaster moving down the hill increases
During a baseball game, a pitcher throws a ball and a batter hits it. The ball flies through the air, hits the ground, and rolls across the grass. The ball has both potential energy and kinetic energy in three of these situations, but it has only kinetic energy in one of the situations. When does the ball have only kinetic energy?
when it rolls across the grass
Francesca hangs three balloons from strings. She gives the first balloon a positive charge. She gives the second balloon a negative charge. She does not give the third balloon a charge. Describe what will happen when she holds a rod with a positive charge near each balloon. Explain why each balloon reacts the way that it does.
The rod will repel the balloon with the positive charge, because they both have the same charge and like charges repel one another. The rod will attract the balloon with the negative charge because they have opposite charges and unlike charges attract one another. The rod will attract the balloon with no charge because a charged object will attract uncharged objects.
Students’ answers should include:
• a description of how a charge on the rod affects each balloon
• an explanation why each balloon reacts the way that it does
• a statement of what happens to a balloon if it has the same charge as the rod
• a statement of what happens to a balloon if it has a different charge from the rod, or no charge
You use energy transformations every day. Which of these is a way that you would use the transformation of electrical energy to motion energy?
A. watching your favorite show on television
B. taking an elevator to the top of a tall building
C. listening to your MP3 player while you walk to school
D. turning on the lamp on your desk so you can see to do your homework
taking an elevator to the top of a tall building
When you plug in your lamp and turn it on, the light does not shine. Which of the following is a possible explanation for the light not coming on?
A. You plugged the lamp into an open circuit.
B. You plugged the lamp into a closed circuit.
C. You plugged the lamp into a series circuit.
D. You plugged the lamp into a parallel circuit.
You plugged the lamp into an open circuit.