8th Grade Science Review, Part 1

The scientist Alfred Wegener hypothesized that all the continents were once joined together in a single landmass and have since drifted apart. This theory became known as

• continental drift.

• continental mass.

• land drift.

• land movement.

Why does a red tomato appear red?

• It absorbs red wavelengths of light.

• It reflects red wavelengths of light.

• It refracts red wavelengths of light.

• It transmits red wavelengths of light.

The diagram shows the waveforms for two sounds. Which statement about sound A and sound B is correct?

• Sound A is louder because its frequency is greater.

• Sound A is louder because its amplitude is greater.

• Sound B is louder because its frequency is greater.

• Sound B is louder because its amplitude is greater.

Scientists use fossils to reconstruct extinct organisms and compare them to modern organisms. The process by which all the different kinds of organisms have changed over long periods of time is called

• sedimentation.

• replacement.

• deposition.

• evolution.

When a light wave hits a surface, part of the wave bounces back in a process called

• reflection.

• refraction.

• resonance.

• repulsion.

Which experimental observation would demonstrate the uniformity of gravitational force on an object at Earth’s surface?

• the constant downward displacement of a falling body

• the constant downward velocity of a falling body

• the constant downward acceleration of a falling body

• the increasing downward acceleration of a falling body

You are planning an experiment to observe the relationship between magnetism and electricity. What question will least help you focus your research?

• How can I use electricity to change the strength of a magnetic field?

• What is needed to make Earth’s most powerful electromagnet?

• Can an electrical charge reverse the direction of a magnetic field?

• What happens to the magnetic field if I turn off the electricity?

Refraction is the bending of light waves due to a change in

• amplitude

• wavelength

• speed

• frequency

A sound wave is an example of a mechanical wave because a sound wave requires

• a mechanical device to be heard.

• a medium through which to travel.

• empty space through which to travel.

• a standing wave to be produced.

Imagine an object is at rest. If two forces push on the object in the same direction, what must be true about the motion of the object?

• The object must remain at rest.

• The object must move at constant velocity.

• The object must accelerate in the direction of the forces.

• The object must accelerate in the direction opposite the forces.