Question

Plz help with the math worth 21 points

Answer 1

As there is one math problem over there.

Lets see the question first:

It says that "A hair dryer is rated
`1200\ W`,if you use the dryer for
`0.25\ h`.How much electric energy do you use ?"

Final answer = Electic energy
`=0.3\ kW\ h`

Explanation:

Electrical Energy
`E=Power * time`.

The total amount of electrical energy used depends on the total power used by the electrical device and the total time they are used for.

So we have been given the power of the hair dryer
`=1200\ W =(1200)/(1000)=1.2\ kW`

Now the time it has been use for
`=0.25\ hrs`

To calculate electric energy we will multiply both the terms.

Electric energy
`=0.12 * 0.25 =0.3\ kW\ h`

So electric energy used for the hairdryer is =
`0.3\ kW\ h`