Estimate the luminosity of a 1 solar mass protostellar cloud, which collapses from an initial radius of 10^3 au down to a solar radius, over a timescale of 40 million years by radiation of its gravitational potential energy, in the units of the present solar luminosity:

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?