What it shows
The distance of a jump depends on the take-off speed and angle. Swinging the arms adds to the speed of the body’s launch, which is why athletes use them.
The science
A jump is a projectile motion. Range is greatest at take-off angles near 45 degrees, but a human jump is closer to 30 degrees because of body mechanics. An arm swing adds momentum and makes the legs push harder against the floor, increasing take-off speed and so the distance.
Materials
Cost: free. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- A soft sand pit or a mat
- A measuring tape
- Chalk for a take-off line
- A notebook
- A helper to measure
- A camera for slow-motion footage
Safety
For this project: Jump onto a soft surface only after warm-up with a teacher present. Stop if you feel any pain; do not compete to break records. This project is not training advice.
Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.
All the safety rulesStep by step
8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.
Mark a take-off line and lay the tape out straight from it.
Warm up for five minutes with light stretching and gentle jumps.
Jump with the arms held still on the hips and measure from the line to the back of the heel.
Repeat three times and write the distances.
Jump with a vigorous arm swing and measure three more times.
Film one jump of each type and compare the take-off angles on a paused screen.
Collect data from five volunteers and compute the average difference.
Draw a bar chart for the two methods for each jumper.
What you should see
The jumps with arm swing are usually longer by 10 to 20 per cent, and the video shows a steeper take-off with greater body stretch.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
1What type of motion is a jump?
Projectile motion.
2Why do arms help?
They add momentum and help the legs push harder.
3Which angle gives the longest range in ideal conditions?
45 degrees.
4Why measure from the heel?
The heel is the point closest to the take-off line.
Take it further
Compare the standing jump with a running jump, and discuss why athletes use a run-up.
Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.
Free ebooks for this project
Science projects
Physics Working Models Explained
Twenty classic models, how each works and how to make it
Science projects
Science Projects for Class 6 to 8
Working models matched to middle-school science topics