Work = (force) x (distance)
Work = (21 Newtons) x (9 meters) = 189 Joules
Power = (work done) / (time to do the work)
Power = (189 Joules) / (3 sec)
Power = (63 watts/sec)
Power = 63 watts (D)
1) The electric potential at a distance r from a single point charge is given by

where k is the Coulomb's constant, q is the charge and r is the distance from the charge.
The charge in this problem is

So the potential at distance

is

2) By using the same formula as before, we can find the electric potential at distance r=99 m from the charge:
Answer:
Mass=3,height=50 and time=15,g=10,P=?
P=mgh/t....which is 3×10×50=1500/15=100Watts
An electric generator works on the principle of Faraday's law of electromagnetic induction. Faraday's law of electromagnetic induction states that “whenever a current carrying conductor are placed in the magnetic field, then a flux is induces in the circuit due to which a current start to flow in the rotor also.
They hit the ground at the same time