[填空题]
In this question distance9 ixsw1t+ mgl5h9ud5fs oc*- :tc7wzl is in centimetres and a.4h3652ky c3qmm5xhpg c sowh8*ffetime is in seconds.
Particle X is moving along a straight line such that its displacement from a point A , after t seconds, is given by $ s_{\mathrm{X}}=24-t-5 t^{3} e^{-0.6 t}$,$ \quad 0 \leq t \leq 30$
This is shown in the following diagram.
1. Find the value of t when particle X first changes direction.
2. Find the total distance travelled by particle X in the first 3.5 seconds.
Another particle, Y , moves along the same line, starting at the same time as particle X . The velocity of particle Y is given by $v_{\mathrm{Y}}=5-t, 0 \leq t \leq 30$ .
3. a. Given that particle X and Y start at the same point, find the displacement function $s_{\mathrm{Y}}$ for particle Y .
b. Find the other value of t when particles X and Y meet.
