Please help me. I've been trying to find an answer for more than an hour now. A Star fleet science officer drops a large rock from a height of 1.55 m onto the surface of an alien planet. The rock strikes the ground in 0.230 s. Determine the acceleration of gravity.

One hazard of space travel is debris left by previous missions. there are several thousand masses large enough to detect by radar orbiting the earth, but there are far greater numbers of very small masses such as flakes of paint. calculate the force exerted by a 0.110 mg chip of paint that strikes a space shuttle window at a relative speed of 5.00 ✕ 103 m/s and sticks, given the collision lasts 6.00 ✕ 10-8 s. such a collision chipped the window of the ill-fated challenger in june 1983, causing $50,000 of damage.