Question

a child is sitting on a swing its minimum and maximum height from the ground are 0. 75 m and 2 m respectively its maximum speed will be

Answer 1

mg(h2-h1)=0.5mv^2
g(2-0.75)=0.5v^2
v= root(1.25g)

Answer will depend upon the value of g you take

Decrease in potential energy = gain in kinetic energy

Answer 2

The maximum swing speed of the child is 5 m/s.

Given:

Minimum height = 0.75 m

Maximum height = 2 m

To Find:

Maximum swinging speed =?

Solution:

When the child goes up the energy stored is the potential energy, there the kinetic energy will be zero.

When the child comes down then the potential energy is been converted into kinetic energy.  

Drop in “potential energy” = maximum kinetic energy

$m g(2-0.75)=\frac{1}{2} m v^{2}$

$v=\sqrt{2g(1.25)}$

$v=\sqrt{(2)\times(9.8)\times(1.25)}$

$v=5 \ m / s$