Question

A 5kg rock is lifted 2m. find the amount of work done? Note that 5kg is a mass not a force

Answer 1

Work done is 98Nm

Step-by-step explanation:

Given:-

• Mass = 5kg
• Displacement = 2m

To Find:-

• Work done

Solution:-

We know that,

`\qquad \boxed{\sf Force=mg}`

where m is the mass, g is the acceleration due to gravity.

Acceleration due to gravity = 9.8m/s² viz. always constant

Substituting the values into the formula we get,

`{\implies \sf Force = 5 * 9.8}`

`{\implies \pmb{\sf Force =49 N}`

Now formula for calculating the work done on an object,

`\qquad \boxed{\sf Work \:done=Force * distance}`

Substituting the values into the formula we get,

`{\implies \sf Work \: done= 49 * 2}`

`{\implies \pmb{\sf Work \: done= 98Nm}}`

Therefore,

`\underline{\sf the\:work\:done\:is\:\pmb{\sf 98Nm.}}`

Answer 2

The amount of work done is 20 joule.

Step-by-step explanation:

Since the work is done against gravity:

Given,

mass(m) = 5kg

height(h) = 2m

gravity(g) = 10m per s²

Work done(W) = ?

We know,

W = mgh

= 5 × 10 × 2

= 20 J