Question

Certain force acting on a 20 kg mass changes its velocity from 5m/s to 2m/s. Calculate the work done by the force.

Answer 1

Answer:

-210 joules

Explanation:

Work done by a given force = change in kinetic energy

Given :

• Mass of the object = 20 kg

• Initial velocity of the object = u = 5 m/s

• Final velocity of the object = v = 2 m/s

To find :

• Work done by the force

Work done by the force = ½mv²-½mu²

Work done by the force = ½×m(v²-u²)

Work done by the force = ½×20(2²-5²)

Work done by the force = 10(4-25)

Work done by the force = 10(-21)

Work done by the force = - 210 Joules

The work done by the force is equal to - 210 Joules

Answer 2

Answer:

Given:

• Certain force acting on a 20 kg mass changes its velocity from 5m/s to 2m/s.

Find:

• Calculate the work done by the force.

Know terms:

1. Mass = (m)
2. Initial velocity = (u)
3. Final velocity = (v)
4. Work done = (a)
5. Joule = (J)

Using formula:

⇒ $\bold{a = \: ^{1/2} mv^2-^{1/2} mu^2}$

⇒ $\bold{a = \: ^{1/2} \times \: m (v^2 -u^2)}$

Calculations:

⇒ $\bold{a = \: ^{1/2} \times \: 20(2^2 -5^2)}$

⇒ $\bold{a = 10(-21)}$

⇒ ${\sf{\underline{\boxed{\red{\sf{ a = -210 \: J}}}}}}$

Therefore, -210 J is the work done by the force.