At what speed would one need to fire a lead project tile in order for its temperature to rise from 25°c to 36.9°c upon impact on a stationary object

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

Asolid cylinder and a cylindrical shell have the same mass, same radius, and turn on frictionless, horizontal axles. the cylindrical shell has light-weight spokes connecting the shell to the axle. a rope is wrapped around each cylinder and tied to blocks of equal masses that are held the same height above the ground. both blocks are released simultaneously. the ropes do not slip. which block hits the ground first? or is it a tie?

Why does lightning travel from clouds to the ground?