If the heater can heat 200 mL of water from 22 ∘C to 91 ∘C in 13.9 min , approximately how much current does it draw from the car's 12-V battery? Assume the manufacturer's claim of 75% efficiency. Express your answer using two significant figures.

Explanation:

First, we will convert 200 ml into kg as follows.

                       200 ml = 0.2 kg

Now, we will take the density of water as 1 g/ml.

And,   dT =

               =

Also, we know that specific heat of water is 4.186 . Therefore, we will calculate the heat energy as follows.

                q =

                   =

                   = 5.77 kJ

Now, we will calculate the power delivered as follows.

                    P =

                       =

                       = 69.1 W

It is given that efficiency is 75%. Therefore, input power will be calculated as follows.

                      = 92.13 W

Now, we will calculate the current as follows.

                 P =

                 I =

                   = 7.67 A

Therefore, we can conclude that current drawn from the car's 12-V battery is 7.67 A.