A sprinter explodes out of the starting block with an acceleration of + 2.02 m/s2, which she sustains for 1.12 s. Then, her acceleration drops to zero for the rest of the race. What is her velocity at (a)t = 1.12 s and (b) at the end of the race?

Constant velocity attained = 2.02*1.12 = 2.26 m/s

That will be her velocity at the end of the race also.

That is a very slow speed for a sprinter. Champions run about four times faster

To find the sprinter's velocity at time (a), we need to calculate the change in velocity during the time the sprinter accelerates. The equation to use is:

v = u + at

Where:
v = final velocity
u = initial velocity
a = acceleration
t = time

Given that the initial velocity (u) is 0 m/s (since she starts from rest) and the acceleration (a) is +2.02 m/s^2, and the time (t) is 1.12 s, we can substitute these values into the equation:

v = 0 + (2.02)(1.12)
v = 2.26 m/s

Therefore, at (a)t = 1.12 s, the sprinter's velocity is 2.26 m/s.

To find the sprinter's velocity at the end of the race (b), we need to know the total time for the race. Since the acceleration drops to zero, we can use the equation:

v = u + at

However, this time we need to find the final velocity (v) when the acceleration (a) is zero. Since the acceleration is zero, the equation becomes:

v = u

The initial velocity (u) is the velocity at (a)t = 1.12 s, which we already calculated. Therefore, the final velocity (v) at the end of the race is also 2.26 m/s.

So, at the end of the race, the sprinter's velocity is 2.26 m/s.