Work by Constant Force

[youngJkim]

Yeah I get my work done when I watch AK Lectures!

[BTWPhysics]

The concept of work in Physics as "what is accomplished" when a force acts on an object to cause a displacement of the object is completely erroneous or wrong and work, hence, is not really force times displacement(F•d). But, what is accomplished if it's not a displacement? Instead, it would be "what is accomplished" when a force acts on an object for a period of time. So, again, what is accomplished?

Work is a vector quantity(i.e. it's not a scalar) and is defined as a "physical-displacement"(ms) by or due to a force, a constant impulse, or a constant kinetic force during or for a time. So, work done is a "physical-displacement" done by or due to a force, a constant impulse, or a constant kinetic force during or for a time. This means that what is accomplished is a physical-displacement(i.e. a matter-displacement). The unit for work is the same as the unit for physical-displacement which is kilogram-meters(k*m) and is not a unit of energy.

So, let's take the example in the video with the box moving forward at a constant velocity. There is a physical-displacement done on the box along the x-axis due to the kinetic force or momentum of the box. We would know this based on the assumption that the box would hypothetically keep moving forward under its own momentum if the person walking was to let go of it. This means that there would be work done by the kinetic force or momentum of the box.

Displacement(s) = vt
Physical-displacement = mass(m) x displacement(s)
Physical-displacement(ms) = mvt

The physical-displacement done or work done by the kinetic force acting for a time would be referred to as kinetic work. We would ordinarily substitute physical-displacement(ms) with a "W" having a lower case "k" as a subscript to represent kinetic-work, but "W" will do. At the same time, we would substitute momentum(mv) with a lower case "k" to represent kinetic-force.

kinetic-work(W) = kt