When a coil of copper wire is turned inside a spinning magnetic field, electric current is created. Explain the observation of the static Ballon activity

Aproton is projected toward a fixed nucleus of charge +ze with velocity vo. initially the two particles are very far apart. when the proton is a distance r from the nucleus its velocity has decreased to 1/2vo. how far from the nucleus will the proton be when its velocity has dropped to 1/4vo?

In a system, when potential energy decreases, then entropy also decreases. true false

What do you think car designers do if the damage caused by a crash test is too severe?