Question

Suppose that Wing Commander abhinandan are 80 kg. If F-16 drops the support of M-21 and jumps to a height of 1000 m. If they fall freely to the height of half the height, then after getting slowed due to the parachute, they reach the final velocity of 10 m / s on the ground, then the work done by the resistance force will be

Answer 1

The Work done by retarding force is 396000 joules.

Explanation :

During first 500 m of free fall of Wing Commander Abhinandan

u = initial velocity = 0 m/sec

v = final velocity

a = g = 10 m/sec²

s = 500 meters

s = ut + at²/2

500 = 0 + 10*t²/2

t = √100 = 10 sec

v = u + at = 0 + 10x10 = 100 m/sec

For the second part of the journey, Wing Commander abhinandan felt retardation to reduce the speed,

s = 500 meters

u = 100

v = 10 m/sec

v² – u² = 2as

a = (10x10 – 100x100)/2x500 = (100 – 10000)/1000 = -9.9 m/sec²

The retardation is 9.9 m/sec².

Work done = Force * distance = Mass * Acceleration * Distance

=> W = 80 x 9.9 x 500 = 396000 joules

Hence the Work done by retarding force is 396000 joules.