Rina's remote-controlled helicopter was on the ground with fully charged batteries. she turned the helicopter on and flew it straight up to its maximum altitude. she continued flying the helicopter at its maximum altitude until its batteries ran out of charge and the helicopter's engines stopped. the helicopter fell toward the ground and got stuck in the branches of a tree. when was the least gravitational potential energy stored between the helicopter and earth?

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.