Suppose a 4000 kg elephant is hoisted 20m above earth's surface. what will be the elephant's gravitational potential energy?

Unpolarized light of intensity i_0=750w/m^2 is incident upon two polarizers. after passing through both polarizers the intensity is i_2=280w/m^2. (a) what is the intensity of the light after it passes through the first polarizer in w/m^2? (b) write an equation for the angle between the polarizers in terms of the initial (i_0) and final (i_2) intensities. (c) find the angle between the polarizers in degrees.

Which of the following is the best name for mgcl2

Ahorizontal force of 400.0 n is required to pull a 1760 n truck across the floor at a constant speed. find the coefficient of sliding friction.