Question

Please answer q 59 and 60?

Answer 1

For Question 59:

`E=8.64xx10^12` `J`, which is answer (D)

For Question 60:

`v=sqrt(u^2+2gh)`

This is answer (A).

Explanation:

For Question 59:

One watt is one joule per second. If the power station produces 100 MW that means it produces `100,000,000=1.0xx10^8` `Js^-1`

In a day there are `24xx60xx60=86,400` seconds.

`P=E/t`, which can be rearranged to `E=Pt`

So the total energy produced in a day is:

`E=Pt=1.0xx10^8xx86,400=8.64xx10^12` `J`, which is answer (D), except that the answer is not written in scientific notation.

For Question 60:

The magnitude of the final velocity will be made up of the initial horizontal velocity, `u`, which will remain unchanged if we ignore air resistance, and a vertical velocity due to gravity.

The vertical component will be given by `v_y^2=u_y^2+2a_ys`

The initial velocity in the vertical direction is `0`, the acceleration is `g` and the distance it falls is `h`, so:

`v_y^2=2gh`

Since these components are at right angles to one another we use Pythagoras' theorem to calculate the magnitude of the final velocity:

`v^2=u_x^2+u_y^2`

`v=sqrt(u_x^2+u_y^2)=sqrt(u^2+2gh)`

This is answer (A).