It’s possible to determine the composition of the ancient atmosphere by analyzing bubbles of air trapped in am- ber, fossilized tree resin. (This is one way that we know that the air in the time of the dinosaurs was richer in oxygen than our current atmosphere.) An air appears to be 7.2 mm below the surface of a piece of amber, with index of refraction 1.54. How long a needle is required to reach the bubble?

Aballoon is rising vertically upwards at a velocity of 10m/s. when it is at a height of 45m from the ground, a parachute bails out from it. after 3s he opens his parachute and decelerates ata a constant rate 5m/s. when. (a) what was the height of the parachutist above the ground when he opened his parachute? (b)how far is the parachutist from the balloon at t=3s? (c)with what velocity does the parachutist hit the ground? (d)after how long does the parachutist hit the ground after his exist from the balloon?