Find the weight of an object with mass 80 kg on the moon ( g = 1.6 m/s^2)

The period of a pendulum varies directly as the square root of the length of the pendulum and inversely as the square root of the acceleration due to gravity. find the period when the length is 144 cm and the acceleration due to gravity is 980 cm per second squared, if the period is 7pi seconds when the length is 289 cm and the acceleration due to gravity is 980 cm per second squared.

How would you find force of the ping pong ball rolling down the track?

When receiving a serve,you ideally want the first pass to be ?