Which of the following instruments can be used to compare the magnitudes of charges on two given bodies?

A body of mass 2 kg is released from a point 100 m above the ground. Calculate its kinetic energy 80m  from the point of release.

Which of the following waves is not mechanical?
 

A loaded spring is set in simple harmonic motion. The force that tends to restore the load to its equilibrium position is

Which of the following cases cannot produce total internal reflection? A light ray travelling from