The big idea: Kick a football, throw a stone off a cliff — with only gravity acting, it's a projectile.
The trick: split it into sideways (steady speed) and up/down (free fall, g = 9.8 m s⁻²).
A horizontal launch: equal sideways steps (constant velocity) combine with growing downward drops (free fall) to trace a parabola.
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Spot it: two columns: Make two columns — horizontal and vertical — and fill each separately.
Horizontal: steady speed (no acceleration). Vertical: free fall (a = g).
They don't interfere — a ball thrown sideways falls exactly like one you drop. The only thing they share is time: use the same t in both.
They don't interfere — a ball thrown sideways falls exactly like one you drop. At every tick they're level, and they land at the same time (same t in both).
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Thrown sideways off a cliff? Just two steps — do the down part first, then the across part. They share one thing: the time.
The method — always two steps
Down → find the time
The fall ignores the sideways speed. Falling from rest, put the height into s = ½gt² and solve for the time t.
Across → find the range
Now use that same t. The sideways speed is steady, so range = speed × t.
down first → then across
- displacement — here the vertical drop / height fallen (m)
- initial velocity — here the vertical part, which is 0 when launched horizontally (m s⁻¹)
- acceleration — here it is g, the 9.8 m s⁻² of free fall (given)
- time of flight (s)
A stone is thrown horizontally at 12 m s⁻¹ from a cliff 20 m high. (Take g = 9.8 m s⁻².)
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How this is tested — split it into sideways + up/down. It comes up two ways:
Paper 1A
- Compare a dropped ball with one thrown sideways.
- Which lands first?
Paper 2
- A full calculation.
- time of flight, range, or impact speed.
The classic trap: Sideways speed does NOT change the fall time. The fall time depends only on the vertical drop (height + g).
Two balls from the same height land together — one dropped, one thrown sideways.
Exactly this question: one ball dropped, one thrown sideways from the same height. They stay level the whole way and land together.
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From the top of the same cliff, ball P is dropped and ball Q is thrown horizontally at the same instant. Which lands first, and why?
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