Explanation:
The gravitational potential energy is given by :
P = mgh
The kinetic energy of an object is given by :

As the ball reaches the bottom of the ramp, its potential energy decreases and kinetic energy increases.
It imply that, when the ball at the top most height, its gravitational potential energy is maximum and zero kinetic energy and when ball reaches the bottom of the ramp, it will have maximum kinetic energy and zero potential energy.
Answer:
(1) By increasing the number of loops of wire around the iron core
(2) increasing the current or voltage.
Answer:

Explanation:
Mass: M, Length: L.

The formula that gives center of mass is

In the case of a non-uniform mass density, this formula converts to

where the denominator is the total mass and the nominator is the mass times position of each point on the rod.
We have to integrate the mass density over the total rod in order to find the total mass. Likewise, we have to integrate the center of mass of each point (xσ(x)) over the total rod. And if we divide the integrated center of mass to the total mass, we find the center of mass of the rod:

Here x's are cancelled. Otherwise, the denominator would be zero.

Recall this equation for a device in a direct current circuit:
P = IV
P is the power dissipated by the device, I is the current through the device, and V is the voltage drop of the device.
If we choose to use the ampere as the unit of current and the volt as the unit of voltage, then the product of the current and the voltage will give the power with watts as the unit.