Question

calculate the work done by a bricklayer who lifted cement block of mass 10kg from the floor to a height of of 2.5m (acceleration due to gravity is 9.8ms²)?

Answer 1

You refered to the acceleration due to gravity as 9.8m/s^2. Another way to look at this is a gravity field unit, on our earth, the gravity field operating on any mass is 9.8 Newtons/kgOf mass, or 9.8N/kg. Because we do not see gravity field strength (with our eyes), we speak often of things we can measure, like distance and time, and say g=9.8m/s^2. In fact, g is gravity field strength (ie "g", get it?), but it is equal to...not this:
<The gravitational field strength at a point is the gravitational force exerted per unit mass placed at that point. This means that the gravitational field strength, g {\displaystyle g} is equal to the force experienced by a mass of 1 kg in that gravitational field>
so work= gravity field strentth* mass moved*distance moved
= 9.8N/kg * 2.5m*10kg.

Answer 2

An object having mass 10 kg is raised to 3m above the ground. Calculate the workdone. (g=10)