Setting up: resolving the initial velocity
Components first. Then use suvat in each direction independently.
The model. A projectile is a particle that, after launch, is acted on only by gravity — no air resistance, no other forces. Its acceleration is therefore constant: vertically downward, horizontally.
Components. Launch speed at angle above the horizontal:
Always draw the right-angled triangle:
u
┌───
/│
/ │ u sin θ
/ │
/θ │
└────┘
u cos θ
Sign convention. Upward positive is conventional. State your convention explicitly in the working — Edexcel mark schemes reward clarity.
Time-independence. Horizontal and vertical motions are completely independent. The same time links them: and .
Why air resistance is neglected. At GCSE the assumption is implicit; at M2 it's stated. Real projectiles experience drag or (Stokes), but this is deliberately excluded from the IAL specification. Any answer that "accounts for air resistance" loses marks because it doesn't match the model.
- Components: horizontal, vertical.
- Horizontal velocity is CONSTANT throughout the flight.
- Vertical velocity changes by per second.
- Declare your sign convention.