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 $25kg$ and initial velocity is $2m/s$. When the distance covered by the body is $4m$, its kinetic energy would be

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

Answer 1

Answer: (A)

$10J$

Initial kinetic energy of the body
$=\frac{1}{2}m{v}^2=\frac{1}{2}\times 25\times 2^2=50J$
Work done against resistive force $=$ Area between $F\times$ graph
$=\frac{1}{2}\times 4\times 20=40J$
Final KE$=$ Initial KE $-$ Work done against resistive force
$=50-40=10J$