Catapult Lab

Explain launch energy and angle

Help your child separate the effect of pullback from the effect of launch angle.

🎯

The strongest launcher is not automatically the best launcher.Accuracy comes from matching energy, mass and angle to the target.

Nallo’s guide for parents

Before the first test

The setup is ready. Ask your child what they expect, then start the test.

Steps

Ask your child: “Will this ball land short of the target, on it or beyond it?”
Start the prepared test after discussing your predictions.
Follow the arm and release together, then compare the landing positions.

Your catapulttarget: 4.0 m

Aim for the target, then launch.Model result · visual scale follows the modeled release height

Make a guess

Prediction

Discuss the observation

Ask your child what changed and what stayed the same.

READYCan you land inside the target zone?

A hit is within 0.35 m of the target center.

Show the numbers

Landing distance——

Launch speed—from stored elastic energy

Peak height—above launch ground

Flight time—until landing

WHAT TO TRYLaunch the starter setup.

If it misses, change one thing: angle, stretch, arm length or projectile.

A closer look at this test

💡What your launch teaches

Range comes from a combination of stored energy, launch speed, angle and air drag.

Run once, then change only the release angle.

What the model teaches

Stored elastic energy becomes rotational energy of the arm and projectile. After release, gravity and air drag shape the trajectory. More stored energy is useful only when it matches the target.

Why does the ball fly?

Stretching the elastic stores energy. The arm swings from behind the pivot toward the target and releases the soft ball.

Try it: change just the release angle. Compare where the ball lands, not only how high it flies.

An explanation to share

How you can explain it

Pulling back stores energy. The arm swings and lets go of the ball. Gravity pulls the ball down while the air slows it. The angle changes how much of the flight goes up or forward.

AngleHow steeply the ball leaves the launcher.

Away from the screen

An activity for you to guide

Choose a clear space with a bowl on the floor and a soft paper ball. Demonstrate gentle hand throws.
Toss the ball gently by hand. Try a low throw and a higher throw from the same place.
Keep throws away from people and animals. Notice where each throw lands.

Explanation guide for parents

Stay with your child throughout the experiment. Read the task together, compare your predictions and start the test. Operate the controls, then discuss what changed.

Support your child’s reasoning

Ask “Was it short or long?” before suggesting a change. Hand tossing is a simple way to explore aiming; children do not need to build a powerful launcher.

Ask: “What did you change? What did you notice? What will you try next?” A different result is a clue, not a bad score.

Screen and real life

The arm motion helps show the launch. Real elastic, joints and soft balls behave less evenly than this model.

Use the simulation to discuss patterns. You remain responsible for choosing and supervising any physical activity; real results can differ.

A question to take it further

Did this change send more of the motion upward or forward?

A common misunderstanding

A higher arc is not always a longer throw. The familiar 45-degree rule does not apply unchanged when air resistance and launch height matter.

How the model works

Simple linear elastic; fixed 68% transfer efficiency; uniform rigid arm with a short lever extension 35% of the throwing-arm length; the ball leaves tangentially at the chosen angle; quadratic air drag; no sling dynamics or frame flex. The arm swings clockwise over the pivot, releases along its tangent and follows through. Gravitational lifting energy is subtracted before calculating speed. A pull that cannot lift the arm does not launch. Swing timing is slowed for viewing; flight uses one uniform spatial scale. Use only soft projectiles in any real classroom activity.

Quick guide: s = seconds · m = metres · cm = centimetres · g = grams · kg = kilograms.

BUILD 20 · PARENT GUIDE · 29 SEP 2026