A body having an initial velocity of 10 m/s moves 200 mm in 5 sec when a force of 20 kgf is applied to it. If the acceleration due to gravity is 9 m/s2 the weight of the body should be
A)15 kg
B)18.35 kg
C)11 kg
D)18.65 kg
E)16.5 kg

Question

Quizplus · Accepted Answer

Explanation:Weight of the body (W) = Force applied (F) - (Mass * Acceleration due to gravity)= 20 kgf - (Mass * 9.81 m/s2)Initial velocity (u) = 10 m/sFinal velocity (v) = 0 m/s (since the body comes to rest after moving 200 mm)Distance covered (s) = 200 mm = 0.2 mTime taken (t) = 5 secUsing the equation of motion, v2 = u2 + 2as02 = 102 + 2 * a * 0.2a = -25 m/s2Therefore, Mass (m) = F/ (a + g)= 20 kgf / (-25 m/s2 + 9.81 m/s2)= 20 kgf / (-15.19 m/s2)= 1.317 kgTherefore, Weight of the body (W) = m * g= 1.317 kg * 9.81 m/s2= 12.9 kgHence, the weight of the body is approximately 13 kg.

A Body Having an Initial Velocity of 10 M/s Moves