7th Gr Practice Test Unit 2 6-11

 When the steel balls hit the paper, what types of energy are some of the KE converted?

• Some of the KE was converted to GE because the balls pushed back.

• Some of the KE was converted to TE because the TE burned a hole in the paper that was between the two steel balls.

• The KE was transferred to the paper and then back to the next steel ball.

• The KE was not converted because the steel balls continued to move after they hit each other.

What determines the amount of thermal energy of an object? Choose all that apply.

• Temperature

• Speed

• Mass

• Springiness

Which object has more thermal energy - a large pot of water or a small pot of water at the same temperature?

• Both pots have the same thermal energy.

• The large pot has more thermal energy.

• The small pot has more thermal energy.

• There is not enough information to answer the question.

Do all solids have thermal energy?

• No, only solids that have heat added to it has thermal energy.

• Yes, all solids have thermal energy.

• All solids, liquids, and gases have thermal energy when the particles move.

• Yes, the particles in solids are always in continuous motion, so they always have kinetic energy. The thermal energy of an object is the total kinetic energy of all its particles.

Why does food coloring spread out faster in hot water than in cold water?

• The food-coloring molecules melt in hot water and spread out.

• The food-coloring molecules expand in hot water and spread out much faster.

• The water molecules move faster in hot water than in cold water, so they collide with the food-coloring molecules more frequently and they spread out faster.

• Because the cold water molecules don’t move as fast as the hot water molecules they block the food coloring molecules from spreading out.

A cold can of soda is taken out of the refrigerator. It slowly warms up until it is room temperature. Once the soda has warmed up, it has more thermal energy than it had in the refrigerator. Where did this additional thermal energy come from?

• The thermal energy was already in the soda.

• The thermal energy came from the air surrounding the soda can.

• The thermal energy came from the air surrounding the soda can and from the soda itself.

• The thermal energy came from the refrigerator.

You have a large mug with hot tea and a small mug with ice tea. Which mug has more thermal energy?

• The small mug because all of the energy is compressed into a smaller region so it gets warmer.

• The large mug with hot tea. The size of the mug does not affect the thermal energy but the temperature of the tea does.

• The large mug with hot tea because the larger vessel will always have more thermal energy.

• The large mug of hot tea because it contains more tea and the tea is hotter.

What energy transformations did you notice when you placed the aluminum foil in the copper chloride solution?

• Thermal energy was converted into chemical energy. We saw the aluminum foil change.

• The chemical reaction released chemical energy which was converted (transformed) into thermal energy. We know this because the temperature of the solution increased.

• Thermal energy was converted to sound energy because we heard the aluminum foil crackle and sizzle.

• The chemical reaction caused thermal energy to be converted to heat energy and sound energy and the thermometer read an increased temperature.

What influences the amount of chemical energy (CE) an object has?

• The size of the beaker and how full of a chemical it is.

• The temperature of the chemical solution.

• The amount and type of chemicals used.

• The size and temperature of the object.

What energy transformations are associated with fireworks? 

• Chemical reactions transform chemical energy into light energy and sound energy.

• Chemical reactions transform chemical energy into thermal and light energy.

• Chemical reactions transform chemical energy into thermal and light energy. The thermal energy also gets transformed into sound energy and kinetic energy of the fireworks pieces.

• Chemical reactions transform chemical energy into kinetic energy and light energy.