Ultraviolet light from the Sun can
A.
damage molecules in skin cells, such as DNA.

B.
damage nerve cells but not skin cells.

C.
cause skin cells to release stinging chemicals.

D.
help skin cells to repair DNA faster.

Why does the input force have to be greater than the force needed to lift the bale?

Why do electron microscopes have higher resolving power than light microscopes?

Ablock of mass m = 2.5 kg is attached to a spring with spring constant k = 710 n/m. it is initially at rest on an inclined plane that is at an angle of θ = 23° with respect to the horizontal, and the coefficient of kinetic friction between the block and the plane is μk = 0.19. in the initial position, where the spring is compressed by a distance of d = 0.16 m, the mass is at its lowest position and the spring is compressed the maximum amount. take the initial gravitational energy of the block as zero. a) what is the block's initial mechanical energy? b) if the spring pushes the block up the incline, what distance, l, in meters will the block travel before coming to rest? the spring remains attached to both the block and the fixed wall throughout its motion.