A child sleds down a frictionless hill with vertical drop h. At the bottom is a level stretch where the coefficient of friction is 0.27.

If she slides 19 m across the level stretch, what's h? Express your answer with the appropriate units.

The speed of light in a material is 0.50 c. what is the critical angle of a light ray at the interface between the material and a vacuum?

Can anybody me with this? ? (picture included.)

Ball bearings are made by letting spherical drops of molten metal fall inside a talll tower-called a shot tower- and solidify as they fall. a-if a bearing needs 4.0 s to solidify enough for impact, how high must the tower be? b- what is the bearing's impact velocity?