Question

A pendulum bob is released from some initial height such that the speed of the bob at the bottom of the swing is 2.7 m/s. The acceleration of gravity is 9.81 m/s^2.
What is the initial height of the bob? Answer in units of m.

Answer 1

Potential energy is the energy possessed by a body while at rest while kinetic energy possessed by a body in motion. In this case the energy of the bob at the highest point is the potential energy while the energy possessed by the bob at the lowest point is the kinetic energy. The potential energy is converted to kinetic energy while the bob sets in motion . Therefore;
      1/2mv²=mgh
     = 1/2 v² =gh
       1/2× 2.7² = 9.81 h
          h = 0.372 m

Answer 2

v squared equals 2gh so the answer gives 2.7*2.7 = 2*9.81*h the answer for the math solution of the speed of the bob at the bottom of the swing being 2.7 is 0.396 meters