A particle travels in a straight line so that, t seconds after passing a fixed point, its velocity, v ms⁻¹, is given by v = e⁴ for 0 ≤ t ≤ 4, v = 16e⁴/t² for 4 < t ≤ k. The total distance travelled by the particle between t = 0 and t = k is 13.4 metres. Find the value of k.
Mark scheme
Marking points from the official mark scheme (May/June 2023). The mark or mark type is shown in brackets.
- [B3] ∫e⁴ dt = 4e⁴(+c) and ∫16e⁴/t² dt = -16e⁴/t (+c)
- [B2] for either correct
- [B1] for ∫e⁴ dt = ae⁴(+c) where a is a constant, a > 0 or ∫16e⁴/t² dt = -b/t (+c) where b is a constant b > 0
- [M1] Correct plan: ∫₀⁴e⁴ dt + ∫⁴ᵏ(16e⁴/t²) dt = 13.4 soi
- [A1] Correct equation: 4e⁴ - 4e⁰ + (-16e⁴/k + 16e⁴/4) = 13.4 OR [When t = 4 s = 4e⁴ - 4 When t = k s = -16e⁴/k + 8e⁴ and] 13.4 = -16e⁴/k + 8e⁴
- [A1] k = 10 or awrt 10.0 dep on all previous marks awarded
Write your answer and get it marked
On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.
Sign up free →