An electric car accelerates for 80 s by drawing energy from

An electric car accelerates for 8.0 s by drawing energy from its 315-V battery pack. During this time, 1140 C of charge passes through the battery pack. Find the minimum horsepower rating of the car.

Solution

Current in the battery pack is

                 I = Q / t = (1140 C ) / ( 8.0 s ) = 142.4 A

Power rating of the car is

                P = I V  

                    = ( 142.4 A ) ( 315 V )

                    = (44887.5 W ) (1 hp / 735.499 W )

                   = 61.02 hp