Question

If mechanical energy is conserved, then a pendulum that has a potential energy of 20 J at its highest point and 0.5 J at its lowest point has _____ as its kinetic energy at its lowest point.
20 J
0.5 J
19.5 J
20.5 J

Answer 1

At the highest point: kinetic energy is 0 due to the speed  is 0

So the total mechanical energy is 20

Assume no frictions present, then the mechanical energy is conserved

So at the lowest point, kinetic energy = mechanical energy - potential energy

Answer will be 20 - 0.5 = 19.5 J