Power is defined as the rate of doing work or the work per unit of time. The first step to solve this problem is by calculating the work which can be determined by the equation:
W = Fd
where:
F = force exerted = ma d = distance traveled m = mass of object a = acceleration
Acceleration is equivalent to the gravitational constant (9.81 m/s^2) if the force exerted has a vertical direction such as lifting.
W = Fd = mad = 63(9.81)(7) = 4326.21 Joules
Now that we have work, we can calculate power.
P = W/t = 4325.21 J / 5 seconds = 865.242 J/s or watts
One path because in a series circuit it is only one path while in a parallel circuit you have 2 or more. Our houses use parallel so that is why you can turn off one light and the rest would stay on.