Physical Sciences (Forces, Energy, Light and Sound) Flashcards

A student pushes a heavy box across a carpet at a constant speed. Which statement best describes the forces on the box?

Answer: The pushing force equals the friction force

At constant speed the forces are balanced, so the push exactly matches friction.

Why does a ball rolling on a smooth tiled floor travel farther than the same ball rolling on grass?

Answer: Tiles produce less friction than grass

Grass creates more friction, which slows the ball faster than a smooth surface.

An astronaut has a mass of 70 kg on Earth. What is the astronaut's mass on the Moon?

Answer: 70 kg

Mass is the amount of matter and does not change with location; only weight changes.

Two magnets are held with their north poles facing each other. What will happen when they are released?

Answer: They push apart

Like magnetic poles repel each other.

A cyclist stops pedaling on a flat road. Why does the bicycle eventually stop?

Answer: Friction and air resistance act against its motion

Friction and air resistance transfer the bike's kinetic energy to heat and sound until it stops.

Which simple machine is a ramp used to load a heavy barrel onto a truck?

Answer: Inclined plane

A ramp is an inclined plane that reduces the force needed by increasing the distance moved.

A parachute slows a skydiver's fall mainly by increasing which force?

Answer: Air resistance

The large canopy catches more air, greatly increasing air resistance (drag).