How to cheer your girlfriend up when she is sad long distance?

Aparticle moves according to a law of motion s = f(t), 0 ≤ t ≤ 12, where t is measured in seconds and s in feet. f(t) = cos(πt/6) (a) find the velocity at time t (in ft/s).

An automobile of mass 2000 kg moving at 30 m/s is braked suddenly with a constant braking force of 10000 n. how far does the car travel before stopping?

If the speed of a particle triples ,by what factor does its kinetic energy increase?