Science Unit 6 Study Guide

What is Friction?

• Friction is a force that slows things down when two surfaces rub against each other.

• It happens everywhere, like when you walk, slide something across a table, or drive a car.

• In your edible car project, friction affects how well your car moves:

  • Axles and car body: If there’s too much friction, the wheels won’t turn well.

  • Wheels and ground: Some friction helps the car move, but too much will slow it down.

  • Wheels and axles: Wheels need to spin easily around the axles. If they stick, the car won’t roll properly.

How to Reduce Unwanted Friction

• Use smooth materials so the axles can spin easily.

• Make sure axles are straight so they don’t rub too much.

• Avoid extra contact between parts that don’t need to be touched.

How to Use Friction to Your Advantage

• Wheels need the right amount of grip to roll instead of sliding.

• The surface your car rolls on matters—too rough and it slows down, too smooth and it might not grip well.

What is Force?

• A force is a push or pull that can make something move, stop, or change direction.

• It is measured in Newtons (N).

Balanced vs. Unbalanced Forces

• Balanced forces: When forces are equal, the object doesn’t move or keeps moving at the same speed.

• Unbalanced forces: When one force is stronger, it causes movement, speeding up, slowing down, or turning.

Newton’s First Law (Law of Inertia)

• Objects stay still or keep moving the same way unless a force changes their motion.

• Example: If a bus suddenly moves forward, standing passengers fall backward because their bodies resist the change.

• Seatbelts: Keep passengers from moving forward too fast in a crash.

Friction Facts

• Air resistance (drag) is friction from air slowing things down.

• Ice is very slippery because it has low friction.

• Lubricants reduce friction to make things move more smoothly.

• Without friction, no energy would be lost as heat, and things would keep moving without slowing down.

Velocity and Acceleration

• Velocity: How fast something moves in a certain direction.

• Acceleration: How quickly velocity changes (speeding up or slowing down).

Reading a Speed-Time Graph

• A steep slope means fast acceleration.

• A flat line means the speed stays the same.

• A downward slope means slowing down.

Motion in Space

• Without air resistance, if you throw a ball in space, it keeps moving forever unless something stops it.

By understanding friction and forces, you can build an edible car that moves smoothly and travels far!