Question

a sprinter with a mass of 80kg accelerates uniformly from 0 m/s to 9 m/s in 3 s. a.)what is the runners acceleration? b.) what is the net force on the runner? c.) how far does the sprinter travel during the 3 s?

Answer 1

Part A: 
Acceleration can be calculated by dividing the difference of the initial and final velocities by the given time. That is,
             a = (Vf - Vi) / t
where a is acceleration,
Vf is final velocity,
Vi is initial velocity, and
t is time

Substituting,
            a = (9 m/s - 0 m/s) / 3 s = 3 m/s²
ANSWER: 3 m/s²

Part B: 
From Newton's second law of motion, the net force is equal to the product of the mass and acceleration,
               F = m x a
where F is force,
m is mass, and 
a is acceleration

Substituting,
              F = (80 kg) x (3 m/s²) = 240 kg m/s² = 240 N

ANSWER: 240 N 

Part C: 
The distance that the sprinter travel is calculated through the equation,
         d = V₀t + 0.5at²

Substituting,
            d = (0 m/s)(3 s) + 0.5(3 m/s²)(3 s)²
             d = 13.5 m

ANSWER: d = 13.5 m