When a diver under the sea shines a beam of light towards the surface of the water the light does not pass through the water- air boundary into the air above but reflects into the sea. State the name of the phenomenon which occurs and briefly explain why it occurs.

Using a wheel and axle, a farmer is trying to lift a bucket of water from the bottom of a well. the larger wheel has a radius of 40 cm compared to the axle that has a radius of 10 cm. if a bucket of water is 50 n, then how much effort is required to raise it? 12.5 n 200 n 2 n 500 n