Question

a bicyclist is moving at a speed of 5.5 m/s. she squeezes the brakes, giving her an acceleration of -2.1 m/s². how fast is the bicyclist going after 0.3 seconds of applying the brakes?

Answer 1

Formula relating time, velocity and acceleration:

Vf = Vi + at (Vf = Final velocity, Vi = initial velocity)

What you're given:
Initial speed, Vi = 5.5 m/s
Acceleration, a = -2.1 m/s^2
Time, t = 0.3 s

Required:
Vf = ?

Plugging in the given information:

Vf = (5.5) + (-2.1)(0.3)
Vf = 4.87 m/s

The bicyclist's speed is 4.87 m/s after 0.3 s.