One light beam has wavelength, λ1, and frequency, f1. another light beam has wavelength, λ2, and
frequency, f2. write a proportion that shows how the ratio of the wavelengths of these two light beams is
related to the ratio of their frequencies.

if you already have the answer to (a), then just work out how many periods there are in 1 minute, and that's the answer to (c).

falling water hydro = water .. spectcular places these plants are

weight of the box is given as

here this is placed on the inclined of angle 42 degree

now this weight will have two components one is along the incline other is perpendicular to it

so here we need to apply a force parallel to incline opposite to its component of weight

so here the component of weight is given as

here we have

so it requires 75 n force to move it upwards