A-LevelMathematicsMechanics9709/42 · Oct/Nov 2024 · Q24 Marks
A block of mass 20kg is held at rest at the top of a plane inclined at 30° to the horizontal. The block is projected with speed 5ms⁻¹ down a line of greatest slope of the plane. There is a resistance force acting on the block. As the block moves 2m down the plane from its point of projection, the work done against this resistance force is 50J. Find the speed of the block when it has moved 2m down the plane.
- (a)Find the speed of the block when it has moved 2m down the plane.[4]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2024). The mark or mark type is shown in brackets.
- [B1] Change in PE = ±20g sin 30×2 [= ±200]
- [B1] For either expression. Do not allow -1/2*20*(v-5)^2.
- [M1] Attempt at work energy equation; 4 terms; dimensionally correct; allow sign errors; PE term must include a component (allow sin/cos mix). Do not allow with -1/2*20*(v-5)^2 for KE.
- [A1] OE, e.g. 2√10. 6.324555.... AWRT 6.32.
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