Energy, collisions, and waves (grade 4) · lesson

Speed and energy

💡 Anything that moves has energy of motion, and the faster it goes, the more energy it has.

A rolling ball has energy because it is moving. We call this energy of motion.

Speed matters. If two balls are the same, the faster one has more energy. It can knock things over harder.

A thing that is sitting still has no energy of motion.

🧠 Let's work it out

What do you think comes next?

💡 When things crash, energy moves from one to another and some turns into sound and heat.

A collision is when two things bump into each other.

In a collision, energy moves. A bowling ball hits the pins. The ball slows down, and the pins fly. The ball gave some of its energy to the pins.

Some energy also turns into sound and a little heat. That is why a crash makes a noise. The energy does not disappear.

🧠 Let's work it out

What do you think comes next?

💡 Energy can move from place to place as sound, light, heat, or a current, and it can change from one kind to another.

Energy can move. Sound carries energy through the air to your ears. Heat moves from a hot stove into a pot. A wire carries electricity to a lamp.

Energy can also change. A lamp turns a current into light. A solar panel turns light into a current.

People build tools to change energy. A pinwheel can spin a small generator. The generator turns that motion into electricity.

🧠 Let's work it out

What do you think comes next?

💡 Waves carry energy from place to place, but the water itself mostly moves up and down.

Drop a pebble in a pond and waves spread out. The waves carry energy across the water.

The water does not travel with the wave. A floating leaf just bobs up and down as the wave goes by.

The top of a wave is the crest. The bottom is the trough. How tall a wave is from its middle is its amplitude. Taller waves carry more energy.

🧠 Let's work it out

What do you think comes next?

💡 People send information by using patterns, like flashes of light or beeps, as a code.

A code is a set of patterns that stand for a message. Both people need to know what the patterns mean.

A short flash could mean yes. A long flash could mean no. Beeps, taps, and light can all carry codes.

The message is in the pattern, not in how bright or loud it is.

🧠 How to think about it

Look for a rule like "short means yes." If there is a rule, the person is using a code to send information.