Gravity is the attraction of every body to every other body due to the masses of each body. The larger the mass, the greater the force. It also depends on the distances: the closer the bodies, the greater the force. Gravity is directed toward the center of a body, and the distance is measured from the center.
When objects fall to the ground, gravity causes them to accelerate. Acceleration is a change in velocity, and velocity, in turn, is a measure of the speed and direction of motion. Gravity causes an object to fall toward the ground at a faster and faster velocity the longer the object falls.
the answer is a) 0.00235 because 1/425=0.00235. hope I helped!
The work done by the machine is equal to the product between the force applied and the distance over which the force is applieds, so in this case:

And the power of the machine is equal to the ratio between the work done by the machine and the time taken: