Date | May 2014 | Marks available | 8 | Reference code | 14M.2.sl.TZ1.6 |
Level | SL only | Paper | 2 | Time zone | TZ1 |
Command term | Find | Question number | 6 | Adapted from | N/A |
Question
Ramiro and Lautaro are travelling from Buenos Aires to El Moro.
Ramiro travels in a vehicle whose velocity in ms−1 is given by VR=40−t2, where t is in seconds.
Lautaro travels in a vehicle whose displacement from Buenos Aires in metres is given by SL=2t2+60.
When t=0, both vehicles are at the same point.
Find Ramiro’s displacement from Buenos Aires when t=10.
Markscheme
METHOD 1
SL(0)=60 (seen anywhere) (A1)
recognizing need to integrate VR (M1)
eg SR(t)∫VRdt
correct expression A1A1
eg 40t−13t3+C
Note: Award A1 for 40t, and A1 for −13t3.
equate displacements to find C (R1)
eg 40(0)−13(0)3+C=60, SL(0)=SR(0)
C=60 A1
attempt to find displacement (M1)
eg SR(10), 40(10)−13(10)3+60
126.666
12623 (exact), 127 (m) A1 N5
METHOD 2
recognizing need to integrate VR (M1)
eg SR(t)=∫VRdt
valid approach involving a definite integral (M1)
eg ∫baVRdt
correct expression with limits (A1)
eg ∫100(40−t2)dt, ∫100VRdt, [40t−13t3]100
66.6666 A2
SL(0)=60 (seen anywhere) (A1)
valid approach to find total displacement (M1)
eg 60+66.666
126.666
12623 (exact), 127 (m) A1 N5
METHOD 3
SL(0)=60 (seen anywhere) (A1)
recognizing need to integrate VR (M1)
eg SR(t)=∫VRdt
correct expression A1A1
eg 40t−13t3+C
Note: Award A1 for 40t, and A1 for −13t3.
correct expression for Ramiro displacement A1
eg SR(10)−SR(0), [40t−13t3+C]100
66.6666 A1
valid approach to find total displacement (M1)
eg 60+66.6666
12623 (exact), 127 (m) A1 N5
[8 marks]