Answer:
D
Explanation:
We know the formula for Work to be:
W = f * d
Where W is work done
f is force
d is the distance
A)
Work = 50
Distance = 50
So, Force is:
Force = 50/50 = 1
B)
Work = 400
Distance = 80
Force = 400/80 = 5
C)
Work = 365
Distance = 73
Force = 365/73 = 5
D)
Work = 144
Distance = 16
Force = 144/16 = 9
Hence, D is the situation in which the force applied is the greatest.
To solve this problem we will apply the concepts related to Coulomb's law for which the Electrostatic Force is defined as,

Here,
k = Coulomb's constant
= Charge at each object
r = Distance between them
As the distance is doubled so,





Therefore the factor is 1/4
We know that arc length (x(t)) is given with the following formula:

Where r is the radius of the barrel. We must keep in mind that as barrel rolls its radius decreases because less and less tape is left on it.
If we say that the thickness of the tape is D then with every full circle our radius shrinks by d. We can write this down mathematically:

When we plug this back into the first equation we get:

We must solve this quadratic equation.
The final solution is:

It is rather complicated solution. If we asume that the tape has no thickness we get simply:
Answer:
20 seconds
Explanation:
The equation for Power is:

Which means...

We can plug in the given values into the equation:

