| Date | May 2009 | Marks available | 1 | Reference code | 09M.1.SL.TZ1.7 |
| Level | Standard level | Paper | Paper 1 | Time zone | Time zone 1 |
| Command term | Question number | 7 | Adapted from | N/A |
Question
A lift (elevator) is operated by an electric motor. It moves between the \({\text{1}}{{\text{0}}^{{\text{th}}}}\) floor and the \({{\text{2}}^{{\text{nd}}}}\) floor at a constant speed. One main energy transformation during this journey is
A. gravitational potential energy \( \to \) kinetic energy.
B. electrical energy \( \to \) kinetic energy.
C. kinetic energy \( \to \) thermal energy.
D. electrical energy \( \to \) thermal energy.
Markscheme
D
Examiners report
There is a popular misconception that a decrease in gravitational potential energy will always be associated with an increase in kinetic energy. As the lift (elevator) descends, the speed is constant and as a result, the kinetic energy of the lift (elevator) remains constant. This does, of course, lead to an interesting opportunity for discussion related to conservation of energy.
