FINAL EXAM REVIEW 7G

A student is investigating how heat transfer from two different materials can affect the rate at which ice melts. The student places a plastic tile and a marble tile next to each other on a table. The student first touches the tiles and records how they feel. Then, the student records the temperature of the tiles. Two ice cubes are removed from the freezer, and one cube is placed on each of the tiles. The initial temperatures of the ice cubes are recorded as well. The picture shows the experiment setup, and the table shows the data collected during the experiment. Which part of the experiment provides evidence of a change in particle motion?

• Both of the ice cubes had the same initial temperatures

• Both of the ice cubes changed state from a solid to a liquid

• The plastic tile had a higher initial temperature than the ice cube on the tile

• The plastic tile took more time to transform the ice cube than the marble tile.

The law of conservation of energy states that when one form of energy is transformed to another,

• energy is destroyed in the process.

• no energy is destroyed in the process.

• energy is created in the process.

• sine amount of energy cannot be accounted for.

People use self-warming and self-cooling devices for many purposes such as keeping drinks cold or food warm. Medical professionals also use these types of devices to store medicines and other substances that need to stay colder than room temperature. These cooling and warming devices use a chemical reaction to produce their chilling and warming effects. Compounds combine in endothermic (heat absorbing) or exothermic (heat releasing) reactions within these devices to help them keep items cool or warm.

Jacob and Natalie are asked by their science teacher to design a warming or cooling device. They decide to design a cold pack that can be used to help keep food cool. Jacob

and Natalie read about different substances that can be used inside cold packs and learn that most cold packs use endothermic reactions to cool objects. They find the table below while researching.

Which sample uses the substance(s) that Jacob and Natalie should use to make a cold pack that will do the BEST job of keeping food cool?

• Sample 1, because it absorbs the most energy

• Sample 2, because it absorbs the most energy

• Sample 3, because it absorbs the least energy

• Sample 4, because it absorbs the least energy

Two students are using a rope model to explain the motion of waves. The students move the ropes up and down as shown in the diagram below. The waves move at the same speed.

Which pattern is the same for both ropes shown?

• Both ropes show waves with the same number of troughs and peaks

• Both ropes show waves that have the same amount of energy.

• Both ropes show waves that move through a liquid.

• Both ropes show waves of the same height.

Visible light is an example of

• chemical energy

• electrical energy

• electromagnetic energy

• nuclear energy

The bending of waves due to a change in speed is called

• reflection.

• diffraction

• refraction.

• Interference.

When you rub your hands together on a cold day, you use friction to transform

• mechanical energy into thermal energy.

• thermal energy into nuclear energy.

• nuclear energy into electrical energy.

• electrical energy into electromagnetic energy.

Students are using a mallet to hit a drum. The diagram below shows this action.

Which statement BEST describes the phenomenon illustrated in the model?

• Sound waves are being absorbed by the drum

• Sound waves are being transferred from the mallet to the drum

• Sound waves are being reflected by the drum

• Sound waves are being transmitted through the air in the drum.

Darla and Rob plan an investigation to see if adding weights to a car affects its speed down a ramp. Their experimental setup consists of a ramp made of a piece of wood that is 30 cm long. The ramp is propped up on four books to give it a height at one end of 8 cm.

What could they be investigating based on the image below?

• the steepness of the ramp.

• the number of books that prop up the end of the ramp.

• the distance the car travels down the ramp.

• the speed at which the car travels down the ramp.

An example of something that stores chemical energy is

• lightning.

• a microwave.

• a match.

• light.