What factors are required for refraction to occur !

Acatapult is tested by roman legionnaires. they tabulate the results in a papyrus and 2000 years later the archaeological team reads (distances translated into modern units): range = 0.4 km; angle of launch = π/5 rad; landing height = launch height. what is the initial velocity of launch of the boulders if air resistance is negligible?

When a light bulb shines, it gives off light energy and energy. a. heat b. potential c. chemical d. electrical

The speed of light can be used to measure the