M2 June 2013 (R) Q2
2. A ball of mass 0.2 kg is projected vertically upwards from a point \(O\) with speed 20 m s\(^{-1}\). The non-gravitational resistance acting on the ball is modelled as a force of constant magnitude 1.24 N and the ball is modelled as a particle. Find, using the work-energy principle, the speed of the ball when it first reaches the point which is 8 m vertically above \(O\). (6)
NB This question tells candidates to use work-energy - suvat approach scores 0/6
| Scheme | Marks |
|---|---|
| \(1.24 \times 8;\ \ \ 0.2g \times 8;\ \ \ \tfrac{1}{2}0.2.20^2\) or \(\tfrac{1}{2}0.2.v^2\) | B1;B1;B1 |
| \(1.24 \times 8 = \tfrac{1}{2}0.2.20^2 - \tfrac{1}{2}0.2.v^2 - 0.2g \times 8\) | M1 A1 |
| \(v = 12\) | A1 |
| (6) | |
| (6 marks) |
Notes
B1;B1;B1 B1 for each term seen or implied 9.92, 15.68, 40 or \(0.1v^2\)
M1 Condone sign errors but all terms should be present
A1 Correct equation