Topic 1.5: Three Launches — Predict Before You Test

Name: _______________________________ Date: _______________ Period: ______

Quick Recap

You already measured how your Nerf car's speed changes over distance back in Week 1. Today you'll use that same car and launcher for three different launches — a flat launch, a table launch, and an angled elevated launch — and before every single one, you have to calculate and mark your prediction BEFORE you see what actually happens.

Materials

Nerf car + launcher (same one from Week 1 — keep it consistent all three tests)
A table/platform of known height (Test 2)
An angled podium/ramp stand of known height and known angle (Test 3)
Meter stick, protractor or angle finder, stopwatch, masking tape
Your Nerf Car Racing Lab (Topic 1.3, Sessions 2-3) data table for reference

Test 1 — Flat Launch: Confirming Launch Velocity

The question: How fast does the car leave the launcher in just the first half-meter — not its average over a long roll?

Mark the starting line and the 0.5 m mark.
Launch 2-3 times, timing only the first 0.5 m each time.

Trial	Time to 0.5 m (s)	$v_i = \dfrac{0.5\text{ m}}{t}$
1
2
3

Average launch velocity (Test 1): ______ m/s

Compare to the first interval (0-0.5 m) of your Nerf Car Racing Lab data. Close? If not, why might it differ today?

Test 2 — Horizontal Table Launch

Setup: Launcher at the edge of a table, launching horizontally.

Measured table height: ______ m Launch velocity used (from Test 1): ______ m/s

Step 1 — Predicted time of fall ($\Delta y = \tfrac{1}{2}gt^2$):

Step 2 — Predicted range ($x = v_it$):

My predicted landing distance: ______ m — mark it with tape BEFORE launching.

Trial	Actual Range (m)
1
2
3

Back-calculate the true launch velocity: the fall time only depends on height, not horizontal speed — so you already knew the time before you launched. Now that you have an actual distance, solve:

$$v_i = \dfrac{x_{actual}}{t}$$

Back-calculated launch velocity (Test 2): ______ m/s

Which velocity do you trust more — Test 1's or this one? Why?

Test 3 — Angled, Elevated Launch (the hard one)

Setup: Launcher on the angled podium — launched at a known angle, from a known height above the floor. Landing height ≠ launch height this time, so "time up = time down" does NOT apply.

Measured launch angle (θ): ______° Measured height above floor: ______ m Launch velocity used (from Test 2): ______ m/s

Step 1 — Components: $v_x = v_i\cos\theta =$ ______ $v_{y,i} = v_i\sin\theta =$ ______

Step 2 — Vertical velocity at impact ($v^2 = v_{y,i}^2 + 2g(\text{height})$):

Step 3 — Time to impact ($t = \dfrac{v - v_{y,i}}{-g}$):

Step 4 — Predicted range ($x = v_x \times t$):

My predicted landing distance: ______ m — mark it with tape BEFORE launching.

Trial	Actual Range (m)	% Difference
1
2
3

% Difference formula: $\left|\dfrac{\text{Predicted} - \text{Actual}}{\text{Actual}}\right| \times 100%$

Analysis Questions

Which test's prediction was closest to reality? Which was furthest off?

Why might the launch velocity estimate have changed (or stayed the same) from Test 1 to Test 2 to Test 3?

Name a specific source of error for Test 3 (angle measurement, height measurement, air resistance, imperfect launch along the podium's angle).

Conclusion

In 2-3 sentences, explain which of your three launch-velocity estimates you trust most, and what made Test 3's prediction harder than Test 2's.