The answer for this question, If I am correct, should be answer "D".
Answer:
a) KE = 888.26J
b) N = 294.5 turns
Explanation:
For the kinetic energy:

The inertia is:

So, the kinetic energy will be:

Now, friction force is:
Ff = μ*N = 0.80*5N = 4N
The energy balance would be:
Kf - Ko = Wf where Kf=0; Ko = 888.26J; and Wf is the work done by friction force.
Wf = -Ff*d = -Ff*N*2*π*R where N is the amount of turns it gives.
Replacing these values into the energy balance:
0-888.26=-4*N*2*π*0.12
-888.26=-0.96*π*N
N=294.5 turns
Answer:
d. 2 hours
Explanation:
because if it travels 100 miles per hour in 1 hour it would travel 200 miles in 2 hours and so fourth.