Question

How much work is needed to be done on a ball of mass 100g to give it a momentum of 10 kgms-1 ?​

Answer 1

Given:

Mass of 100 grams was given a momentum of 10 kg m/s.

To find:

Work done ?

Calculation:

• Let initial velocity be 0 m/s.

• Final velocity = P/m = 10/0.1 = 100 m/s.

Now , as per WORK-ENERGY THEOREM,

• The work done will be equal to the change in kinetic energy of the body.

$\rm W = \dfrac{1}{2} m {v}^{2} - \dfrac{1}{2} m {u}^{2}$

$\rm \implies W = \dfrac{1}{2} m {(100)}^{2} - \dfrac{1}{2} m {(0)}^{2}$

$\rm \implies W = \dfrac{1}{2} \times 0.1 \times {10}^{4}$

$\rm \implies W = 500 \: joule$

So, work done is 500 Joule

Answer 2

Answer:

• 500 J is the work done.

Explanation:

Given :

Mass (m) = 100g = 0.1 Kg

Momentum (p) = 10 Kg m/s

To find :

Work done (W)

Solution :

Initial velocity (u) = 0 m/s

• Momentum = Mass × Final velocity

10 = 0.1 × Final velocity

Final velocity = 10/0.1 = 100 m/s

• Work-Energy theorem:
• W = 1/2 mv² - 1/2 mu²

W = 1/2(0.1)(100)² - 1/2(0.1)(0)²

W = 1/2(1000) - 1/2(0.1)(0)

W = 500 J is the work done.