Kinetic energy problem?

Question

A toy car has a Kinetic Energy of 12 Joules. What is the KE after a frictional force of 0.6 newtons acted on it for 5 minutes?

Answer 1

The work done by a constant frictional force = F*d.

d = v0*t-.5*a*t^2

a = F/m

d= v0*t - (5*F*t^2)/m

From the initial kinetic energy
v0 = √(2E0/m)

Then d = √(2*E0/m)*t - (.5*F*t^2)/m

E = E0 - F*[√2*E0/m)*t - (.5*F*t^2)/m]

Use t = 5*60 seconds for consistency with joules and newtons.
It appears you need to know the mass of the car.

Answer 2

kinetic energy=1/2*m*v^2
12=1/2*m*v^2
sqrt(24/m)=v(initial velocity)

For a constant force F which moves an object in a straight line from x1 to x2 , the work done by the force can be ,
work=f*(x2-x1)
work=0.6(x2-x1)
force=m.a,where a =acceleration due to gravity.
0.6=m.v1/300^2
0.6*300*300/m=v1

Answer 3

0.3J