A sled drops 20 mts in height on a hill. The rider is going 20 m/s at the bottom of the hill. Where can you find kinetic and potential energy? In which moments?

Density of salty water as compared to the density of pure water is(a) is less(b) is always equal(c) is always more(d) may be less or more

50 g of ice at 0°c is dropped in a beaker containing 100 g of water at 0°c. what will be the contents of the beaker after 5 hours? assume that the room temperature is 0°c.

Does anyone know how to solve this problem? i really need . i made an attempt but i just cant get it. a metal rod is 25.000 cm long at 25.0 degrees celsius. when heated to 102.0 degrees celsius, it is 25.054 cm long. what is the coefficient of linear expansion for this metal.