Year 7 Science · Unit 3 · Lesson 13

Forces and Energy

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Learning Goals

Warm Up

Real-world context

At a skate park in Western Sydney, a rider pumps hard at the bottom of a half-pipe, climbs all the way to the top of the ramp, pauses for a split second, then rolls back down and shoots up the other side. After many runs without pushing again, the rider notices each climb reaches a little lower than the last, until they finally roll to a stop near the middle.

(a) At the very top of the ramp, where the rider pauses, what kind of energy is the rider mostly holding? Explain how it got there.

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(b) Each climb reaches a little lower than the last. Using the idea that energy is conserved, explain where the "missing" energy actually goes.

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Your Turn

Because… chain

Fill in the missing effects in the boxes below. Each cause leads to the next step in the chain. Then write the overall outcome at the bottom.

You pull a slingshot back, applying a force that stretches the elastic band
→
You let go, and the stored energy is suddenly released
→
The stone flies across the clearing and skids along the ground
→
The stone finally comes to rest on the dirt
→

Overall outcome, in one sentence, explain why the total amount of energy stays the same the whole time.

Show What You Know

1. Two students push on a parked car. Student A pushes hard but the car does not move. Student B pushes and the car rolls forward. Which student has done work in the scientific sense, and why? Explain using the idea of energy transfer.

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2. Describe the energy changes when you lift a book onto a high shelf and then let it fall back off. Name the kinds of energy at each stage and the forces involved.

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Wrap Up

In one sentence, what was the main idea of this lesson?

HSCScience · Year 7 Science · Unit 3 · Lesson 13 · Apply Worksheet