A particle P moves in a straight line from a fixed point O. The velocity v m s⁻¹ of P at time t s is given by v = t² – 8t + 12 for 0 ≤ t ≤ 8.
- (i)Find the minimum velocity of P.[3]
- (ii)Find the total distance travelled by P in the interval 0 ≤ t ≤ 8.[7]
Mark scheme
Marking points from the official mark scheme (May/June 2019). The mark or mark type is shown in brackets.
- [M1] Differentiate to find a
- [M1] Set a = 0 and solve for t
- [A1] Minimum v = −4 ms⁻¹
- Alternative method for question 5(i)
- [M1] Attempt to complete the square for v
- [M1] Choose the t value which gives minimum v
- [A1] Minimum v = −4 ms⁻¹
- [M1] Find values of t when v = 0, factorise or formula
- [A1] t = 2 or t = 6
- [M1] Integrate v to find s
- [A1] Correct integration
- [M1] Attempt to find s1, s2 and s3 Look for consideration of the need for 3 intervals Allow use of symmetry when finding s1, and s3
- [A1] 2 correct values of displacement
- [A1] All correct
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