Question

A block of mass m is pulled vertically up with constant velocity of 5 m/s with the help of a string. Work done by the string in 2 second will
be​

Answer 1

Answer:

h=v*t

 =5*2

 =10m

work done by rope =mgh

                                =10mg J

Answer 2

Given:

• Mass of block is m
• Velocity of pulling is 5 m/s.
• Time taken is 2 seconds.

To find:

Work done by string ?

Calculation:

When the string is pulling the object upwards, the work done by th string gets stored in the mass in the form of GRAVITATIONAL POTENTIAL ENERGY.

• So, height attained in 2 seconds = v × t = 5 × 2 = 10 metres

Now, work done is :

$\therefore \: W = PE$

$\implies \: W = m \times g \times h$

$\implies \: W = m \times 10\times 10$

$\implies \: W = 100m\: Joules$

So, work done by string is 100m Joules.