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

Answer: (B)

60 J

Answer 2

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