1) A 1000kg car is at the top of a hill, where its elevation above the bottom of the hill is 120m.
a) What is its gravitational poetential energy?
b) If the cart starts from rest and rolls down the hill with negligible friction and air resistance, what will its kinetic energy be when it reaches the bottom?
c) What will be its speed when it reaches the bottom?
d) Suppose instead that there is noticeable friction and air resistance. The amount of work done on the car by the frictional and air resistance forces as it rolls down the hill is 500,000J.
What then is the kinetic energy of the car when it reaches the bottom of the hill?
e) What would be its speed at the bottom of the hill?
2) A force acts on a 1.5kg cart while the cart moves 1.2m. The work done by the force during the motion is 3J. When the force begins to act on the cart, the cart is already moving with a speed of 1m/s.
a) What is the kinetic energy of the cart at the end of the 1.2m motion? Show your calculations and give units.
b) What is the speed of the cart at the end of the motion? Show your calculations and give units.
c) What is the magnitude of the average on the cart during the motion?