Which is true about UVA and UVB rays? A. Both rays can be blocked 100% by sunscreen
B. UVA protects the surface, UVB protects beneath the surface
C. UVB rays cause burning, UVA rays cause premature aging
D. UVA rays cause burning, UVB rays cause premature aging

I need help :

Asap and show ! a 14 kg rock starting from rest free falls through a distance of 5.0 m with no air resistance. find the momentum change of the rock caused by its fall and the resulting change in the magnitude of earths velocity. earth mass is 6.0 * 10^24 kg. show your work assuming the rock earth system is closed.

Which pair of quantities includes one quantity that increases as the other decreases during simple harmonic motion?

(a) if the pressure in gas is doubled while its volume is held constant, by what factor do (i) vrms and (ii) change? (b) is it possible to boil water at room temperature (20oc) without heating it? explain.