← Back to course
Sports Physics 6-8 / Week 12 / Wednesday
3/6
Week 12 · Design a Landing Pad

Wednesday

Field Lab: Build and test
// Criteria, constraints, build, test, improve
⏱ about 20 min

Wednesday: Field Lab: Build and Test

The tray on the patio is full. Folded paper on the bottom, a rolled towel around the edge, a small cushion on top.

Rocket stands with his toes at the drop spot and the ball level with the tape mark. "Baseline first," Raven reminds him.

He drops onto the bare patio. The ball springs up and Raven calls out the height. Three times, three numbers.

Then the tray slides into place. Rocket drops again. The ball sinks into the cushion and barely lifts.

"What do you notice?" Raven asks, already writing. "That is less than a quarter of the baseline."

Nova hovers above the tray. "Now the car," she says. "Same ramp, same push, and let the pad do the stopping."

Your mission

Today you build your prototype landing pad and run two fair tests: the drop test and the roll test.

Each test has a bare floor baseline and a pad trial, three times each. You record every number.

  • A cardboard tray, box lid or shallow box, no bigger than a tray
  • Soft fillings: folded paper, rolled socks, a small towel, a small cushion, cotton or scrap fabric
  • Tape, scissors for a grown-up, a tennis ball or foam ball, a small toy car
  • One book for the ramp, a tape measure, masking tape marks and your Field Log
Safety first
Drop only from standing reach, at your tape mark. Never climb a chair, step, railing or fence to drop anything.
Soft balls only. Nothing is thrown. The toy car rolls on the floor, never toward stairs or a road.
A grown-up does any cutting. Keep the test area clear of feet, pets and younger children.
Stop if anyone is hurt or tired.
  1. Build your pad inside the tray. Keep it within the size constraint and use only your listed materials.
  2. Baseline drop: hold the ball at the tape mark, let go, and watch the bounce against the tape measure. Record the height.
  3. Repeat the baseline drop two more times. Circle the middle value.
  4. Pad drop: slide the pad onto the drop spot and drop three times from the same mark. Record each bounce and circle the middle value.
  5. Baseline roll: place the car at the top of the ramp and let go without pushing. Measure from the ramp end to where it stops.
  6. Repeat twice more and circle the middle value.
  7. Pad roll: put the pad at the ramp end and roll three times. Measure the stop distance each time and circle the middle value.
  8. Compare each pad result with its baseline and with your criteria. Write "met" or "not yet" beside each criterion.
PREDICT BEFORE YOU TEST
  • Read the question.
  • Tap your answer.
Compared with the bare floor, how high do you predict the ball will bounce on your pad?
The toy car rolls onto the pad instead of the bare floor. Its stop distance will probably be:
TestTrial 1Trial 2Trial 3Middle valueCriterion met?
Drop on bare floor: bounce height (cm)baseline
Drop on pad: bounce height (cm)
Roll on bare floor: stop distance (cm)baseline
Roll on pad: stop distance (cm)

Reading the result

The ball pushed your pad, and your pad pushed the ball back just as hard. That pair never changes. The time did.

The soft filling let the stop take longer, so the push at any moment was smaller and the ball lost its bounce.

In week 8 you saw that a dropped ball never bounces back to its drop height. Some motion energy becomes warmth and sound every time.

A soft pad turns even more of that motion energy into warmth and sound. Very little is left to lift the ball.

If a criterion says not yet, that is useful data. Tomorrow you change one thing to chase it.

What the lab showsTrue or false?
The pad changed how long the stop took.?
The pad made the ball push harder than the pad pushed back.?
A result that misses a criterion is still useful data.?
The bare floor test was the baseline for comparison.?
WHY THIS EXERCISEYour data only means something because the test was fair and had a baseline.
How many trials did you run for each test? Type a number.
WHY THIS EXERCISERepeating trials is how you tell a real result from a lucky drop.
Draw your pad in cross section, layer by layer, and mark where the ball landed.

Real engineering. Tomorrow you read how engineers soften stops, then change one thing and test again.

← Tuesday