Question

If the mass of an object is 50 kg and its velocity changes from 50 m/s to 90 m/s, then find the work done by the object?​

Answer 1

Answer :

The required work done by the object is 140 kN.

Explanation :

Given :

• The mass of an object is 50 kg
• The velocity of the object changes from 50 m/s to 90 m/s

To find :

the work done by the object

Solution :

 The work energy theorem states that work done by the object is equal to the change in Kinetic Energy of the object.

m = 50 kg

u = 50 m/s

v = 90 m/s

Initial Kinetic Energy,

  $\tt KE_1=\dfrac{1}{2}mu^2 \\\\ \tt KE_1=\dfrac{1}{2} \times 50 kg \times (50 m/s)^2 \\\\ \tt KE_1=25 \times 2500 \ N \\\\ \tt KE_1=62500 \ N$

Final Kinetic Energy,

 $\tt KE_2=\dfrac{1}{2}mv^2 \\\\ \tt KE_2=\dfrac{1}{2} \times 50 kg \times (90 m/s)^2 \\\\ \tt KE_2=25 \times 8100 \ N \\\\ \tt KE_2=202500 \ N$

The change in Kinetic Energy,

ΔKE = KE₂ - KE₁

ΔKE = 202500 - 62500

ΔKE = 140000 N

ΔKE = 140 kN

∴ The work done by the object is 140 kN