Question

A worker does 300 J of work against a frictional retarding force of 15 N in

pushing a box across a floor in 3s. If the box moves with a constant

speed, how fast is it?

​

Answer 1

Answer:-

• Constant speed of box = 6.67 m/s

Explanation:-

Given:

• The Work done by worker, W = 300 J
• Retarding frictional force, F = 15 N
• Time for which boxed is pushed, t = 3 s

To find:

• Constant speed of box, v =?

Formulae required:

• Formula to calculate work

        W = F . s

• The Formula for calculating constant speed

        v = s / t

[ Where W is work done, F is the force applied, s is distance covered, v is constant speed, t is the time taken ]

Solution:

Using the formula for Work done

→ W = F . s

→ 300 = 15 × s

→ s = 20 m

Now, Using the formula for constant speed

→  v = s / t

→ v = 20 / 3

→ v = 6.67 m/s        

Therefore,

• Constant speed of box is 6.67 m/s.