Answer:
300 J
Explanation:
Work = (Force)*(distance) = 600 N ∗ 0.5 m = 300 J
A) 
The total energy of the system is equal to the maximum elastic potential energy, that is achieved when the displacement is equal to the amplitude (x=A):
(1)
where k is the spring constant.
The total energy, which is conserved, at any other point of the motion is the sum of elastic potential energy and kinetic energy:
(2)
where x is the displacement, m the mass, and v the speed.
We want to know the displacement x at which the elastic potential energy is 1/3 of the kinetic energy:

Using (2) we can rewrite this as

And using (1), we find

Substituting
into the last equation, we find the value of x:

B) 
In this case, the kinetic energy is 1/10 of the total energy:

Since we have

we can write

And so we find:

Answer:
Explanation:
A motor converts electrical energy to mechanical energy. A current carrying coil is placed between electromagnets. A magnetic force is exerted on the coil which makes it rotate. The direction of current changes twice during the rotation of the coil. An outside source of electric current is used.
Thus, the wrong statement is D. It converts mechanical energy into electrical energy. It is the generator which converts mechanical energy into electrical energy.