Question

a motorcyclist sees a branch in the road and hits the brakes, slowing down at -6.42 m/s. if it takes him 2.85 us to stop, what was his starting velocity

Answer 1

Acceleration: -6.42 m/second squared. [ a ]
Final Velocity: 0 m/s [ v ]
Time: 2.85 s. [ t ]
Initial/ starting velocity: ? [ u ]

v = u + a x t
By substituting above values,

0 = u + -6.42 x 2.85
0 = u + (-18.297)
0 = u - 18.297
u = 18.297


Starting velocity = 18.297 m/s