A spring launcher can fire a foam ball from floor level with one fixed compression. (a) Formulate a focused research question about launch angle and horizontal range. [2] (b) Give a reasoned hypothesis using horizontal and vertical velocity components. [3] (c) Design a safe method using angles from 15° to 75°, identifying the independent, dependent and at least three controlled variables. Include repeats and a results table or graph plan. [6] (d) Explain one important limitation and a specific improvement. [3] Do not invent results.

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Vary only launch angle, measure horizontal range to first impact, and keep launch speed, release height, ball and landing level constant. A model without drag predicts a maximum near 45°, but the experiment must test that prediction. (a) A focused question is: How does launch angle from 15° to 75° affect the horizontal range of a foam ball launched at constant speed from and to the same height? (b) At low angle the horizontal component is large but flight time is short; at high angle flight time is longer but the horizontal component is small. The ideal no-drag model therefore predicts a maximum near 45°. (c) Set 15°, 25°, 35°, 45°, 55°, 65° and 75° with a securely clamped launcher and protractor. Fire into a clear, supervised landing lane and mark the first impact, not the bounce. (c) The independent variable is angle and the dependent variable is horizontal range. Control spring compression, ball, launcher position, release height, landing height and the rule used to locate impact. (c) Take at least five independently reset launches per angle. Record every range with units, calculate a mean and range, and plot mean range against launch angle with the spread shown. (d) The launcher may not give identical speed after each reset. Measuring launch speed with video or two light gates would reveal this variation; randomising the angle order also separates drift from an angle effect. (d) Wear eye protection, never aim at people, use a light foam projectile and establish a no-entry landing zone before firing.

Which launch angle gives the greatest range?

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