A-LevelMathematicsMechanics9709/52 · Feb/Mar 2019 · Q15 Marks
A particle is projected with speed 24 m s¯¹ at an angle of 30° above the horizontal. Find the speed and direction of motion of the particle at the instant 4 s after projection.
- (a)A particle is projected with speed 24 m s¯¹ at an angle of 30° above the horizontal. Find the speed and direction of motion of the particle at the instant 4 s after projection.[5]
Mark scheme
Marking points from the official mark scheme (Feb/Mar 2019). The mark or mark type is shown in brackets.
- [B1] Use horizontal motion
- x' = 24cos30 ( = 12 √3 )
- [B1] Use vertical motion
- y' = 24sin30 - 4g ( = -28)
- [M1] Where V is the required speed
- V² = (24cos30)² + (24sin30-4g)² = (12√3 )² + (-28)²
- OR tana = (24sin30 – 4g)/(24cos30) = -28/(12√3)²
- [A1]
- V = 34.9 m s-1
- [A1]
- a = 53.4° below the horizontal
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