Question

A 2-kg bowling ball is 1 meter off the ground on a post when it falls just before it reaches ground it is travelling 4.4 m/s assuming there is no air resistance which statement is true
mechanical energy is not conserved
initial potential energy is greater than final kinetic energy
mechanical energy is conserved
initial potential is less than the final kinetic

Answer 1

Answer : (C) "mechanical energy is conserved".

Explanation :

It is given that :

Mass of the ball, m = 2 kg

Velocity, v = 4.4 m/s

Height, h = 1 m

Mechanical energy is the sum of kinetic energy and the potential energy. It is related with the position and the motion of the body.

So, $Total\ energy = Kinetic \ energy +potential \ energy$

In this case, the mechanical energy or the total energy of the ball remains conserved. This is termed as conservation of Mechanical energy.

$TE=\dfrac{1}{2}mv^2+mgh$

$TE=\dfrac{1}{2}\times 2\ kg\times (4.4)^2\ m/s+2\ kg\times 9.8\ m/s^2\times 1\ m$

$TE=38.96\ J$

So, the correct option is (C) "mechanical energy is conserved and it is equal to 38.96 J".

Answer 2

mechanical energy is E=mgh+ 1/2 mV²=2*9.8*1+1/2*2*4.4²=38.96J, 
the only force is P, that is a conservative force so the answer is
mechanical energy is conserved and its value is 38.96J,