The length, L of a simple pendulum which is about 0.5m can be measured within 1mm. What accuracy is required in the measurement of the periodic time, T of 100 oscillations if the errors in L and T are to produce equal percentage in the calculated value of acceleration due to gravity, g?​

In a game of pool, ball a is moving with a velocity v0 of magnitude v0 = 15 ft/s when it strikes balls b and c, which are at rest and aligned as shown. knowing that after the collision the three balls move in the directions indicated and assuming frictionless surfaces and perfectly elastic impact (that is, conservation of energy), determine the magnitudes of the velocities va, vb, and vc.