Teacher's notes and answers to questions in the book - Hodder Plus ...

WJEC GCSE Additional Science Teacher’s Notes
PRACTICAL Measuring, plotting and analysing real
distance–time graphs (pages 171–72)
A student will need to be primed to bring in a bicycle (with helmet) before-hand. This practical
task requires quite a lot of organisation – a schematic diagram of who is doing what and
standing where will help considerably – go through this in the laboratory before going outside.
A suitable data recording sheet could look like:
Motion
Walking
Running
Cycling
Time to
reach 5 m
cone (s)
Time to
reach 10 m
cone (s)
Time to
reach 15 m
cone (s)
Time to
reach 20 m
cone (s)
Time to
reach 25 m
cone (s)
Time to
reach 30 m
cone (s)
1 2 3 Av 1 2 3 Av 1 2 3 Av 1 2 3 Av 1 2 3 Av 1 2 3 Av
Answers to the ‘Analysing your results’ questions will depend on the results gathered.
_ Velocity–time graphs (pages 172–74)____________
Question
7. Describe the motion of the objects illustrated by the velocity–time graphs in Figure 15.8. For each graph
calculate any accelerations/decelerations and (HT only) the total distance travelled.
a (Top left) Object stationary for 2 s then accelerating at 3 m/s 2 for 2 s, reaching
maximum velocity of 6 m/s, then travelling at constant 6 m/s in same direction
for 6 s
b (Middle left) Object accelerating at 3 m/s 2 for 3 s, reaching velocity of 9 m/s, then
travelling at a constant 9 m/s in the same direction for 4 s before decelerating
(in the same direction) at 3 m/s 2 (or accelerating at –3m/s 2 ) for 3 s before
coming to rest at t = 10 s
c (Bottom left) Object accelerating at 4 m/s 2 for 2 s, reaching velocity of 8 m/s, then
decelerating (in the same direction) at 2 m/s 2 (or accelerating at –2m/s 2 ) for
4 s before accelerating again at 3m/s 2 in the same direction for 3 s reaching a
velocity of 9 m/s before decelerating (in the same direction) at 9 m/s 2 before
coming to rest at t = 10 s
d (Top right) Object initially travelling at 9 m/s, decelerating at 3 m/s 2 for 3 s, coming to
rest at t = 3 s, then accelerating (in the same direction) at 2 m/s 2 for 4 s
reaching a velocity of 8 m/s and then travelling at this constant velocity for 3 s
e (Top right) Object travelling at a constant velocity of 6 m/s for 3 s then accelerating at 2
m/s 2 for 1 s, reaching velocity of 8 m/s and staying at this constant velocity of
8 m/s for 1 s before decelerating (in the same direction) at 2 m/s 2 (or
accelerating at –2m/s 2 ) for 4 s before coming to rest at t = 9 s
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