1) The power needed to accelerate a projectile from rest to is launch speed v in a time t is 43.0 W. How much power is needed to accelerate the same projectile from rest to launch speed of 3 v in a time of 1/2t?
2) A ball is fixed to the end of a string, which is attached to the ceiling at point P, which is at the top. The ball is positioned below it, what enables it to go back to point P?