A particle of mass 500 g is moving in a straight line with velocity $v = \mathrm { b } x ^ { \frac { 5 } { 2 } }$. The work done by the net force during its displacement from $x = 0$ to $x = 4 \mathrm {~m}$ is (Take $\mathrm { b } = 0.25 \mathrm {~m} ^ { \frac { - 3 } { 2 } } \mathrm {~s} ^ { - 1 }$).\\
(1) 2 J\\
(2) 4 J\\
(3) 8 J\\
(4) 16 J