Posted by Emily Shinavier on .
The ball launcher in a pinball machine has a spring that has a force constant of 1.50 N/cm.
The surface on which the ball moves is inclined a = 14.5o with respect to the horizontal. If the spring is initially compressed 4.70 cm, find the launching speed of a 0.113 kg ball when the plunger is released. Friction and the mass of the plunger are negligible.

College Physics 
Hoisan,
If we assume the mass of the ball is proportional to how many significant digits there are in the problem (3), we can assume the mass is around 3, using the formula Ek = m/2v^2 we can find the answer to be 8.