Date | November 2015 | Marks available | 2 | Reference code | 15N.2.hl.TZ0.9 |
Level | HL only | Paper | 2 | Time zone | TZ0 |
Command term | Write down | Question number | 9 | Adapted from | N/A |
Question
A particle can move along a straight line from a point O. The velocity v, in ms−1, is given by the function v(t)=1−e−sint2 where time t≥0 is measured in seconds.
Write down the first two times t1, t2>0, when the particle changes direction.
(i) Find the time t<t2 when the particle has a maximum velocity.
(ii) Find the time t<t2 when the particle has a minimum velocity.
Find the distance travelled by the particle between times t=t1 and t=t2.
Markscheme
t1=1.77 (s)(=√π (s))andt2=2.51 (s)(=√2π (s)) A1A1
[2 marks]
(i) attempting to find (graphically or analytically) the first tmax (M1)
t=1.25 (s)(=√π2 (s)) A1
(ii) attempting to find (graphically or analytically) the first tmin (M1)
t=2.17 (s)(=√3π2 (s)) A1
[4 marks]
distance travelled =|∫2.506…1.772…1−e−sint2dt|(or equivalent) (M1)
=0.711 (m) A1
Note: Award M1 for attempting to form a definite integral involving 1−e−sint2. To award the A1, correct limits leading to 0.711 must include the use of absolute value or a statement such as “distance must be positive”.
In part (c), award A1FT for a candidate working in degree mode (5.39 (m)).
[2 marks]
Total [8 marks]