Question

A body of mass 1 kg falls from a height of 240m with an initial velocity of 14m/s

and penetrates into sand to a depth of 0.2m. Determine the mean resistive force

of the sand by applying the law of conservation of energy.​

Answer 1

mass=1kg

height=240m

U=mgh. {at 240 m}

=1×240×10 {g=10ms^2}

=2400J

The potential energy of the stone at height 240 m = the kinetic energy of the bullet just before hitting the ground.

So, KE of the bullet when it hits the ground = 2400 J

The resistive force (say, F) offered by the sand will work to reduce the KE of the bullet to zero.

So, F×S = 2400 J ['S' is the distance through which stone buries]

Since, F and S are directed oppositely, so,

-F × 0.2 = 2400

=> -F(0.2) = 2400

=> F = - 12000 N

If this is correct , please mark me brainliest ☺️