4. A sled slides without friction down a small, ice-covered hill. If the sled starts from rest at the top of the hill, its speed at the bottom is 7.50 m/s.
(i) On a second run, the sled starts with a speed of 1.50 m/s at the top. When it reaches the bottom of the hill, is its
speed 9.00 m/s, more than 9.00 m/s, or less than 9.00 m/s?
(ii) What is the height of the hill?
(iii) What is the speed at the bottom of the hill?