ankushmittal

chap seven q eleven twelve thirteen fourteen

A lightweight electric car is powered by twelve 4 V batteries. At aspeed of 76 km/h,
the average frictional force is 1140 N.
What must be the power of the electric motor if the car is totravel at a speed of 76 km/h? Answer in units of kW.

My answer was 24.054 kW. if it helps. Now this is my question Icannot get.

What is the “driving cost” if the cost of recharging the batteriesis $0.4 /kW · h?
Answer in units of /km.

Will rate lifesaver for correct answer!

A race car driver must average 203.0 km/h over the course of a time trial lasting ten laps. If the first nine laps were done at 197.0 km/h, what average speed must be maintained for the last lap? (Answer to the nearest km/h.)