What condition must hold for these formulae to apply?

The acceleration must be constant, in a straight line.

A ball is thrown up and lands below its start. What is the sign of s (up positive)?

Negative, since the displacement is downwards from the start.

How do you handle a journey whose acceleration changes?

Split into stages; the final velocity of one stage is the initial velocity of the next.

What is true about two particles when one overtakes the other?

They have equal displacements from the same starting point at that time.

What do you do with a quadratic in t that gives two roots?

Reject any root that is negative or physically impossible.

Constant acceleration formulaeEdexcel International A Level Maths: Flashcards

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State the five variables used in constant acceleration problems.

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State the five variables used in constant acceleration problems.: $s$ (displacement), $u$ (initial velocity), $v$ (final velocity), $a$ (acceleration), $t$ (time).
Write the formula connecting $v$ , $u$ , $a$ and $t$ .: $v=u+at$
Write the formula that does not contain $v$ .: $s=ut+\frac12at^2$
Write the formula that does not contain $u$ .: $s=vt-\frac12at^2$
Write the formula that does not contain $t$ .: $v^2=u^2+2as$
Write the formula that does not contain $a$ .: $s=\frac12(u+v)t$
What condition must hold for these formulae to apply?: The acceleration must be constant, in a straight line.
What value of $g$ is used in Edexcel IAL Mechanics?: $9.8$ m s⁻²
What is the velocity of a ball at its highest point?: Zero (momentarily at rest).
A ball is thrown up and lands below its start. What is the sign of $s$ (up positive)?: Negative, since the displacement is downwards from the start.
How do you handle a journey whose acceleration changes?: Split into stages; the final velocity of one stage is the initial velocity of the next.
What is true about two particles when one overtakes the other?: They have equal displacements from the same starting point at that time.
When is the distance between two moving particles greatest or least?: When their speeds are equal.
What do you do with a quadratic in $t$ that gives two roots?: Reject any root that is negative or physically impossible.

Exam questions on Constant acceleration formulae

A cyclist moves along a straight horizontal road. At the instant she passes a point $A$ her speed is $4$ m s⁻¹. She then accelerates uniformly at $0.5$ m s⁻² for $12$ s.
Find the distance the cyclist travels in the last $2$ s of this motion.2 marks
A ball is thrown vertically upwards with speed $14$ m s⁻¹ from a point $2$ m above horizontal ground. Model the ball as a particle moving freely under gravity, and take $g=9.8$ m s⁻².
Find the speed of the ball when it hits the ground.2 marks
A train moves in a straight line from rest at station $P$ to rest at station $Q$ . It accelerates uniformly at $0.5$ m s⁻² for $40$ s, then travels at constant speed for $150$ s, and finally decelerates uniformly at $0.8$ m s⁻² to rest at $Q$ .
Find the distance travelled by the train while it is decelerating.3 marks

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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).