Paper 3 · Work, Energy and Power
The same cyclist and bicycle (total mass 69.0 kg, kinetic energy 1.04x10^3 J at the top) roll down without pedalling to level ground 4.6 m below the top. Taking g = 9.81 m/s^2, calculate the kinetic energy at the bottom of the rise.
Model answer
4150 J
Also accepted: 4.15 x 10^3 J, 4160 J
Explanation: Lost gravitational PE converts to KE: Ek(bottom) = Ek(top) + mgh = 1.04x10^3 + 69.0 x 9.81 x 4.6, approximately 4.15x10^3 J.
Derived from ZIMSEC Physics Paper 3, November 2004, Q1