Conservation of mechanical energy
Answers are for parents and teachers.
1
Speed at the ground of a body falling from rest from h = 80 m (g = 10), m/s?
40
2
A body thrown up at υ₀ = 40 m/s rises to what height (g = 10), m?
80
3
When a pendulum is pulled aside and released, how does the energy change?
At the extreme E_p is large and E_k = 0; at the bottom E_k is large and E_p small; the sum (without friction) is constant.
4
Why does speed grow when rolling down a hill?
Potential energy turns into kinetic energy.
5
Why use brakes, a helmet and pads when going downhill on wheels?
Speed and E_k grow; a fall can cause serious injury.