Where should the fulcrum be located in this lever to get the greatest mechanical advantage? A. At position II, because the effort arm and the load arm should have equal lengths.
B. At position IV, because the effort should be applied as close to the fulcrum as possible
C. At position I, because the length of the effort arm should be greater than the length of the load arm.
D. At position III, because the length of the load arm should be greater than the length of the effort arm.

you'd use the equation that establishes a relationship between  energy  and  wavelength, which looks like this

e=h⋅cλ, where

λ  - the wavelength of the photon; c  - the speed of light, usually given as  3⋅108m/s; h  -  planck's constant, equal to  6.626⋅10−34j s

plug the value you were given for the energy of the photon in the above equation to get the wavelength

e=h⋅cλ⇒λ=h⋅ce

λ=6.626⋅10−34js⋅3⋅108ms−1.257⋅10−24j=1.581⋅10−1m

the moving of the box is a result of centripetal force. think of that  as a car or a truck in this case creates a turn, the force of friction performing upon the turned wheels of the car runs centripetal force obligatory for circular motion for the things inside it.