Kinetic Energy Grows With the Square of Speed

Lab Brief #2

🎯 Your mission

Predict it first. Then prove yourself right (or wrong).

⚡ The twist

Energy never disappears — it just hides somewhere else.

What you'll learn

Kinetic energy is ½mv². Because speed is squared, doubling a car's speed quadruples its kinetic energy — and roughly quadruples its braking distance. That single relationship is the physics behind most speed limits.

Key words

kinetic energy
The energy an object has because of its motion, ½mv².
braking distance
The distance a vehicle travels while the brakes bring it to rest.

Make a hypothesis first

Before you start: which will move faster, and why?

Say your guess out loud — then find out if you were right.

Get ready

🧰 What you need

trolley
foam blocks
ramp
metre rule
stopwatch

Get ready

⚠️ Safety first

Keep hands out of the crush zone during each run.

Step 1 of 4 · Read

Think about what you just learned: say what "kinetic energy" and "braking distance" mean in your own words before you start.

Step 2 of 4 · Do

Roll a trolley into a foam barrier at three measured speeds and record the crush depth each time. Plot crush depth against speed and then against speed squared, and identify which gives the straighter line.

Step 3 of 4 · Observe

Record what actually happened, including anything that did not match what you expected.

Step 4 of 4 · Record

Write a conclusion that answers the question this lesson opened with, and state your uncertainty.

Question 1 of 2

A car doubles its speed. Its kinetic energy becomes:

How sure are you?😐 maybe

Question 2 of 2

A 2 kg object moves at 6 m/s. Its kinetic energy is:

How sure are you?😐 maybe

Mind = blown

⚡ Static electricity is the same physics as lightning, just smaller.

Nice work!

You got 0 of 2 right.

Next: Gravitational Potential Energy All lessons

🎯

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✨ More to explore

🌍 Where you see this in real life: You use this every time you flip a light switch, ride a bike, or kick a ball.

🏆 Stretch challenge (try it this week): Time how long a small ball rolls down something, then change the slope and try again.

👨‍👩‍👧 For the dinner table: “Show me something at home that uses this kind of energy.”

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Kinetic Energy Grows With the Square of Speed

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