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 ageing.
​d. UVA rays cause burning, UVB rays cause premature ageing

True or false graphs must include scales that increase by the same amount

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.

Which of the following is not a physical property of mattera. melting pointb.heat of combustionc. viscosityd. boiling point