Q. Given that the position of the body in metre is a function of time as follows $x = 2t^{4} + 5t + 4$ The mass of the body is 2 kg. What is the increase in its kinetic energy one second after the start of motion?

A) 168 J
B) 169 J
C) 32 J
D) 144 J
Explanation

(d) $x = 2t^{4} + 5t + 4 = v = \frac{dx}{dt} = 8t + 5$
At $t = 0,v = 5\ m/s$
At $t = 1s,\ v = 8 \times 1 + 5 = 13\ m/s$
Increase in KE
$= \frac{1}{2}m\left\lbrack \left( 13^{\ } \right)^{2} - (5)^{2} \right\rbrack = 144\ J$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.