The short answer
Describing motion with the SUVAT equations — and the projectile traps that catch people out.
Written and checked by GAMSAT tutors — not AI-generated.
Try the reasoning style
We treat forgetting as a failure — a lapse to be patched with reminders and records. Yet a mind that kept everything could not think; it would drown in the undifferentiated noise of every moment it had ever lived. To forget is not so much to lose information as to decide, mostly without our noticing, what was never worth keeping.
The author's argument relies most directly on which unstated assumption?
Pick an option to see how the tutor reasons to the answer — not just whether you were right.
Not quite — the answer is B.
Work backwards from the conclusion: a mind that ‘kept everything’ supposedly ‘could not think.’ That only follows if thinking means leaving most of experience out — so B is the premise the argument quietly rests on. A raises reliability, which the passage never weighs; C contradicts ‘mostly without our noticing’; D smuggles in a claim about intellect the passage never makes. The question rewards finding the hidden premise, not recalling a fact.
Kinematics describes motion — position, velocity and acceleration — without worrying about the forces causing it. When acceleration is constant (which includes free fall), a set of four equations (the SUVAT equations) handles almost everything.
The SUVAT equations
For constant acceleration, with = displacement, = initial velocity, = final velocity, = acceleration, = time: ; ; . Pick the equation that contains the three things you know plus the one you want — and avoids the quantity you don't have.
The projectile trap
At the highest point of a throw, the velocity is zero for an instant — but the acceleration is still (≈ 9.8 m/s², downward). Gravity never switches off. Also: vertical and horizontal motion are independent — a dropped ball and a horizontally-thrown ball hit the ground at the same time.
Solving a kinematics problem
1. List your SUVAT
Write down s, u, v, a, t — fill in what's given. Set a clear positive direction (often 'up is positive').
2. Identify the unknown
What is the question asking for, and which quantity is neither given nor wanted?
3. Pick the equation
Choose the SUVAT equation that excludes the quantity you don't have and don't need.
4. Solve and sanity-check
Watch signs (a downward g is negative if up is positive) and check the answer is physically reasonable.
Worked example
A ball is thrown straight up at 20 m/s. Taking g = 10 m/s², how high does it rise? (Use up as positive.)
Check yourself
A ball is thrown vertically upward. At the highest point of its flight, its velocity and acceleration are:
Key takeaways
- Kinematics describes motion; SUVAT equations apply when acceleration is constant.
- v = u + at; s = ut + ½at²; v² = u² + 2as.
- Pick the equation that omits the variable you neither know nor want.
- At the top of a throw: velocity = 0, but acceleration = g (downward).
- Horizontal and vertical motion are independent — solve them separately.
Practise this with real GAMSAT-style questions
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