What is the transfer of energy in the form of rays or waves.?

If jerome is swinging on a rope and transferring energy from gravitational potential energy to kinetic energy, is being done.

Give one example to show that when substances are mixed,it may result in a chemical or a physical change depending on the conditions.

Two pans of a balance are 24.1 cm apart. the fulcrum of the balance has been shifted 1.33 cm away from the center by a dishonest shopkeeper. by what percentage is the true weight of the goods being marked up by the shopkeeper? assume the balance has negligible mass. answer in units of %.