G student pushes a 80 Kg crate across the classroom floor a distance 5 m at constant speed of 0.4 m/s . If the coefficient of kinetic friction between the crate and the floor is 0.9, how much work did she do

The work done is W = 3528J.

Explanation: Work (W) is an amount of energy used to do determined movement. To calculate it, we use the formula, as the movement is horizontal:

W = F.d, where

F is force on the object

d is distance it went through.

The force acting on the crate is due to friction.

= μ .

μ is the kinetic friction

is the normal force

There is no up and down movement, so , with g = 9.8m/s²

= μ . m . g

= 0.9 . 80 . 9.8

= 705.6 N

Substituing  into the work formula, we have:

W = . d

W = 705.6 . 5

W = 3528 J

The work done to move the crate across a distance of 5m is 3528 J.