Review

Front

What is the distance light travels in one Earth year?

Back

A light-year is about 6 trillion miles.

Front

What is the force that opposes motion between two surfaces in contact?

Back

Friction is the force that opposes motion.

Front

In the presence of unbalanced forces, an object will move in the direction of which force?

Back

The object will move in the direction of the larger force.

Front

What causes scientific knowledge to change?

Back

Scientific knowledge changes with new evidence or new interpretations.

Front

If an object is stationary, what can be said about the forces acting on it?

Back

The forces acting on it are balanced.

Front

What is inertia?

Back

Inertia is the tendency of an object to resist changes in its state of motion.

Front

What is momentum?

Back

Momentum is the product of an object's mass and its velocity.

Front

What is gravity?

Back

Gravity is the force that attracts two bodies towards each other.

Front

What is a galaxy?

Back

A galaxy is a massive system of stars, stellar remnants, interstellar gas, dust, and dark matter.

Front

What is the universe?

Back

The universe is all of space-time and its contents, including planets, stars, galaxies, and all forms of matter and energy.