IB Physics Mark Scheme
2a: Motion and Forces
IB 2009-2014
2.1.1 Motion Graphs
1D
4D
6C
9B
18 A
19 D
21 B
22 C
29 A
33 D
39 B
42. [3 marks]
attempt at area under graph;
appropriate triangle 175 m;
a comment about missing area making answer a little less / OWTTE;
43a. [2 marks]
average speed is the speed over a period of time/distance; instantaneous speed is the speed at a particular
instant in time/point in space.
43b. [3 marks]
(i) speed=(area under graph =)½×7.5×3;
=10 or 11 or 11.3 (ms-1);
(ii) suitable curve approximating to v=kt2;
2.1.2 Equations of Motion
8A
11 C
23 D
24 D
25 D
30 D
45a. [2 marks]
;
;
Award [1 max] for 91m or 91.25m (candidate adds cliff height incorrectly).
45b. [3 marks]
time to reach maximum height=1.5s;
time to fall 91m=4.3s;
total time=5.8s;
Answer can be alternatively expressed as 3.0 (to return to hand) +2.8 (to fall 80m).
or
use of s=ut+½at2;
80=-15t+5t2 or −80=15t−5t2;
t=5.8s;
1
IB Physics Mark Scheme
2a: Motion and Forces
2.1.3 Projectile Motion
7C
10 D
15 B
20 C
26 B
27 D
40 A
44a. [3 marks]
(i) zero;
(ii) horizontal: any horizontal line not on t-axis (accept lines above or below t-axis);
vertical: any diagonal line starting at origin (accept positive or negative gradients);
44b. [4 marks]
(i)
t=4.690≈4.7s;
(ii) sx=uxt=5.0×4.690;
sx=23m;
44c. [3 marks]
;
lower maximum height;
lower horizontal range;
asymmetrical with horizontal range before maximum height more than horizontal
range after maximum height;
2
IB 2009-2014
IB Physics Mark Scheme
2a: Motion and Forces
IB 2009-2014
2.1.4 Terminal Velocity
2B
12 B
14 C
17 A
28 B
32 B
34 A
35 C
41a. [3 marks]
(i) s=12.5/12.6 (m);
Allow g =10ms-2 , answer is 12.8.
(ii)
or gt; (allow any use of suvat equations)
;
Award [2] for a bald correct answer.
Allow g = 10ms-2 answer is 16.0 ms-1.
Allow ECF from (a)(i)
41b. [3 marks]
straight line to water surface; (allow a slight curve within 10 % of t1 ) clear decrease after hitting surface; (allow
straight line or concave curve as shown, do not allow convex curve)
constant non-zero speed reached smaller than maximum; (speed must be less than maximum velocity)
Do not penalize answers where a curve is drawn to the dotted lines as there should not be a discontinuity at the
two lines. Do not penalize if the line continues to t2 or zero velocity shown at t2.
3