Question

The graph between the resistive force F acting on a body and the distance covered by the body is shown in the figure. The mass of the body is 25 kg and initial velocity is 2 m/s. When the distance covered by the body is $5 m$, its kinetic energy would be

• A. 50 J
• B. 40 J
• C. 20 J
• D. 10 J

Answer 1

Answer: (D)

10 J

Answer 2

Initial kinetic energy of the body

$= \frac { 1 } { 2 } m u ^ { 2 } = \frac { 1 } { 2 } \times 25 \times ( 2 ) ^ { 2 } = 50$J

Final kinetic energy = Initial energy – work done against resistive force (Area between graph and displacement axis)

$= 50 - \frac { 1 } { 2 } \times 4 \times 20 = 50 - 40 = 10$ J.