A girl on a swing varies in height from 60 cm above the ground to 180 cm. The girl's greatest velocity is?
A. 1.5m/s B. 4.8 m/s C. 24m/s D. depends on its mass

Question

A girl on a swing varies in height from 60 cm above the ground to 180 cm. The girl's greatest velocity is?
A. 1.5m/s     B. 4.8 m/s    C. 24m/s   D. depends on its mass

jmcs1985 · Answer

Concept question - another way to approach this is to determine where kinetic energy is greatest, and potential energy is lowest.$$KE=\frac{ 1 }{ 2}mv ^{2}$$ and $$U=mgh$$ where KE is kinetic energy in Joules, m is the mass, v is the velocity, U is potential energy, also in Joules, g is acceleration due to gravity, and h is the height.

    Therefore, by comparing the heights, the girl's greatest velocity is at 60cm.