Question

A 4900-lbs car on a level road is tripling its speed. Let Kl and Kf be the car's initial and final kinetic energy, respectively. What is the total work done on the car?[2pt] After a pleasant day at the beach, you carry your 14. 0-kg surf board across the parking lot to your car, a distance of 31. 0 m. What is the work done by you on the surf board?[2pt] After reaching your car, you lift your 14. 0-kg surf board up by 1. 70 m to put it on the roof top carrier. What is now the work done by you on the surf board?[2pt] A child weighs 275N. what is the child's

Answer 1

5) Velocity tripled so $K_{f} = 9K_{i}$

Total work done = $K_{f} - K_{i}= 8K_{i}$ , Option B

6) We dont apply any force in the direction of displacement, only perpendicular to it. So no work done. Option B.

7) Now work is done against gravity = m*g*h = $14*1.7*9.8 = 233.24J$ . Option A is close