What is the total work Wfric done on the block by the force of friction as the block moves a distance L up the incline? Express the work done by friction in terms of any or all of the variables μ , m, g, θ, L, and F1.

diagram is missing, but i will try to explain your doubt.

answer:

amplitude is the maximum displacement or distance moved on a point of a vibrating body or wave measured from its equilibrium position.it is equal to half the length of vibration path.

in simple terms, the principle states that the buoyancy force on an object is equal to the weight of the fluid displaced by the object, or the density of the fluid multiplied by the submerged volume times the gravitational acceleration, g. this is also known as upthrust.

the answer is a. at the equator