An inclined plane 3m high. If a kid sits at its top what will be his potential energy

Can somebody explain to me how newton's 3rd law relates to momentum? ~ap physics 1

Acoyote chasing a rabbit is moving 8.00 m/s due east at one moment and 8.80 m/s due south 4.25 s later. let the x axis point due east and the y axis point due north. find the direction of the coyote's average acceleration during that time.

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.