Question

How mush work is done in lifting a 40 kilogram weight to a height of 1.5 meters?

Answer 1

The answer is `588J`.

Always start with the definition:

`W=int_a^b F(x)dx`

Sometimes, the simple problems are the hardest because it looks too easy so we tend to add unnecessary things. Since this is a vertical lift, we are dealing with gravity which is 9.8 `m/s^2`. So,

`F(x)=9.8m/(s^2)*40kg=392N`

Remember that work is force times distance. We have force which is just a constant function. And we have distance which is `dx`. The tendency is to add an `x` into `F(x)=392N`, but that would be incorrect. Now, let's put it together:

`a=0`
`b=1.5`
`W=int_0^(1.5) 392 dx`
`=392x|_0^(1.5)`
`=588J`