Aparallel-plate capacitor having circular plates of diameter d and a distance d apart stores energy u when it is connected across a fixed potential difference. if you want to triple the amount of energy stored in this capacitor by changing only the size of its plates, the diameter should be changed to:

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.