Question

a cyclist is travelling at 15 ms-1 she applies brakes so that she doesn't collid with a wall 18 m away . What deceleration must she have?

Answer 1

using 3rd equation of motion
$v {}^{2} = {u}^{2} + 2as$
as v=0m/s
u=15m/s
let a be deaccelaration
s=18m
substituting in equation
${15}^{2} + 2 \times a \times 18 = 0$
a=-225/2×18=6.25 m/s^2

so he should deaccelarate with 6.25m/s^2

if found useful mark brainleist