Question

Oh cyclist is travelling at 15 metre per second she applies brakes so that she does not colloid with wall 18 metre away what declaration must she have

Answer 1

here initial velocity =u=15 m/s

v=0

distance = s=18 m

v^2=u^2+2as

0-225=2×18×a

a=-225/36

a=-6.25m/s^2

6.25 m/s^2 retardation

Answer 2

As she is already moving then it is clear that she must have Initial Velocity.

Initial Velocity (u) = 15 m/s

Final Velocity (v) = 0 m/s

Distance (S) = 18 m

By applying third equation of Motion :-

=> V^2 = u^2 + 2aS

=> 0^2 = (15)^2 + 2 x a x 18

=> 0 = 225 + 36a

=> -225 = 36a

=> a = -225/36

=> a = -6.25 m/s^2

Hence, the cyclists have retarded at 6.25 m/s^2