Projectile motion

Release angle, speed and height: what makes a throw or jump go far.

The outline, topic by topic

Each topic is weighted the way the exam weighs it.

Parabolic path: what is it?
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Without air resistance, a projectile follows a parabola.
Only weight acts once released.
A shot-putter releases at 2 m high. Is his optimal angle 45°?
- No, a little less, around 40°
- Yes, always 45°
- No, a little more, around 50°
- No, much less, around 25°
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No, a little less, around 40°
Releasing above the landing lowers the optimal angle: about 42° in theory at 13 m/s. The best throwers even release at around 37 to 38°, as they push less fast upwards.
Release speed: what is it?
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The projectile's speed at release.
It is the most important factor in distance.
Why do long jumpers take off around 20°, far from 45°?
- A low angle always gives a greater range
- They cannot keep their speed if they take off steeper
- Taking off steeper would shorten their flight time
- The rules forbid them to take off above 25°
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They cannot keep their speed if they take off steeper
Taking off at 45° would need as much vertical as horizontal speed: the take-off creates only 3 to 4 m/s of it, against 9 to 10 m/s of run-up. Speed counts more than angle: the angle is sacrificed to keep it.