Question

Calculate the work done to change the velocity of an object of mass 1000 kg from 20m/s to 30 m/s

Answer 1

Answer:

Given:

Mass = 1000 kg

Initial Velocity = 20 m/s

Final Velocity = 30 m/s

To find:

Work done

Concept:

As per Work-Energy Theorem , we can say that in a non inertial reference frame, the work done by all forces is equal to the change in Kinetic Energy of the object

$\boxed{ \sf{ \red{work = \Delta \: KE}}}$

Calculation:

Initial Kinetic Energy

= ½ m (v1)²

= ½ × 1000 × (20)²

= 500 × 400

= 200000 J

= 200 KJ

Final Kinetic Energy

= ½ m (v2)²

= ½ × 1000 × (30)²

= 500 × 900

= 450000 J

= 450 KJ

So work done

= KE2 - KE1

= 450 - 200

= 250 KJ

So final answer :

$\boxed{ \large{ \sf{ \blue{ \bold{work = 250 \: KJ}}}}}$

Answer 2

$\large{\underline{\underline{\mathcal\green{QUESTION::}}}}$

Calculate the work done to change the velocity of an object of mass 1000 kg from 20m/s to 30 m/s.

$\large{\underline{\underline{\mathcal\red{SOLUTION::}}}}$

➡ Here ,apply work - energy theorem.

➡ .°. $\large\red{\boxed{w = ΔKE}}$

NOW,

➡ IN A FIRST PART.

➡ K. E 1 = ½m(v1)²

➡ K. E 1 = ½ × 1000 × (20)²

➡ K. E 1 = 200000j

➡.°. $\large\green{\boxed{K. E 1 = 200kj}}$

➡ IN A SECOND PART.

➡ K. E 2 = ½m(v2)²

➡ K. E 2 = ½ × 1000 × (30)²

➡ K. E 2 = 450000J

➡ .°. $\large\red{\boxed{ K. E 2 = 450kj}}$

NOW,

➡ W = ΔKE

➡ W = ΔKE

W = KE 2 - KE1

W = 450 - 200

$\large\purple{\boxed{ .°. W = 250 KJ.}}$

So,

$\huge\orange{\boxed{\boxed{work = 250kj}}}$