Power question involving sprinter

1. A 50.0 sprinter, starting from rest, runs 56.0 in 9.40 at constant acceleration
What is the magnitude of the horizontal force acting on the sprinter?
What is the sprinter's power output at 1.10 , 3.70 , and 5.20 ?

2. Homework Equations
I would imagine f=ma and possibly some kinematics for part a, and then P= work/t

3. The Attempt at a Solution :
I cant find the force which seems to be the hardest part

LowlyPion
Homework Helper
1. A 50.0 sprinter, starting from rest, runs 56.0 in 9.40 at constant acceleration
What is the magnitude of the horizontal force acting on the sprinter?
What is the sprinter's power output at 1.10 , 3.70 , and 5.20 ?

2. Homework Equations
I would imagine f=ma and possibly some kinematics for part a, and then P= work/t

3. The Attempt at a Solution :
I cant find the force which seems to be the hardest part

You know F = M*a, so what is the constant acceleration?

X = 1/2*a*t2

I'm assuming the units on the three numbers in your first line are kg, m, and s respectively?

You're going to want to find the acceleration a first using one of your kinematics equations. Then identify the mass from your given information and plug m and a into your equation for force.