Question

A body of mass $05\, kg$ travels on straight line path with velocity $v=\left(3 x^2+4\right) m / s$ The net workdone by the force during its displacement from $x =0$ to $x =2 \,m$ is :

• A. 64 J
• B. 60 J
• C. 120 J
• D. 128 J

Answer 1

The Correct Option is B

The correct option is (B) : 60 J 
v_i = 3(0)² + 4 = 4          ≅ x = 0
v_F = 3(2)² + 4 = 16       ≅ x = 2
\(W=ΔK=\frac{1}{2}m(16^2-4^2)\)
\(=\frac{1}{2}\times\frac{1}{2}(256-16)=\frac{240}{4}\)
\(=60\ J\)