motion for ks3 science y7

1. How fast?
10 cm/s
103 m/s = 370 km/h
12 m/s
900 km/h
75 m/s = 270 km/h 7.7 km/s
What do all of these speed units have in common?

2. Measure the average speed of the toy car on a level surface in m/s
Measure the average speed of a falling ball in m/s.
Was the ball moving at this speed the whole trip?
Distance (cm)
Time (s) Average Speed
(cm/s)
Trial 1 Trial 2 Trial 3 Average
Distance (cm)
Time (s) Average Speed
(cm/s)
Trial 1 Trial 2 Trial 3 Average

3. PRACTICAL: Motion Down a Ramp

4. WARM-UP: Speed of a Falling Ball
A ball is dropped from a height of 200 cm. The time of fall is measured
three times. The results are shown in the data table below.
a. What is the average time of fall?
b. What is the average speed of the ball?
c. Is the speed of the ball just before it hits the ground greater than,
less than, or equal to the average speed?
Distance (cm)
Time (s) Average Speed
(cm/s)
Trial 1 Trial 2 Trial 3 Average
200 0.63 0.59 0.62

5. NOTES: UNIT P2.3: Motion

6. NOTES: UNIT P2.3: Motion
• Measuring Motion
• average speed (vavg) – total distance travelled in a particular
time
𝒗𝒂𝒗𝒈 =
𝒕𝒐𝒕𝒂𝒍 𝒅𝒊𝒔𝒕𝒂𝒏𝒄𝒆
𝒕𝒐𝒕𝒂𝒍 𝒕𝒊𝒎𝒆
• instantaneous speed (v) – speed at one particular instant in
time
UNITS: m/s
Does a speedometer
measure average speed
or instantaneous speed?

7. NOTES: UNIT P2.3: Motion
• Measuring Motion
• Ex Prob: A runner completes a 42.2 km marathon in 2.5 hours.
a. What was their average speed in km/h?
b. What was their average speed in m/s?
c. Did the runner run at this speed the whole race?

8. NOTES: UNIT P2.3: Motion
• Measuring Motion
• Have you ever looked out the window of a stationary tram at a
moving tram and felt that you were moving?
• relative motion – the speed of an object compared to
another object
A car on a highway is traveling at 130 km/h and maintaining the
same distance behind another car. What is their relative speed?
A car moving at 50 km/h along a street is approaching another car
moving at 30 km/h in the opposite direction. What is their relative
speed?

9. PRACTICAL: Motion Down a Ramp
• Create graphs
• Work on ‘Conclusion and Evaluation’ questions
• Due Tues 18.5

10. PRACTICAL: Motion Down a Ramp
• Create graphs
• Work on ‘Conclusion and Evaluation’ questions
• Due Tues 18.5
Extension: Answer the Summary Questions on p99 of the Activate
Physics book

11. WARM-UP: Chuck the Ant
Chuck the ant is walking along a meter stick. A graph of his distance vs.
time is shown below.
a. During what times is
Chuck at rest?
b. During what times is
Chuck moving the
fastest?
c. What is Chuck’s average
speed for the whole trip
(in cm/s)?

12. NOTES: UNIT P2.3: Motion
• Graphing Motion
• Distance-time graph
at rest
Ex: Find speed from
4 to 7 sec
𝑣𝑎𝑣𝑔 =
𝑑
𝑡
6 m
3 s
=
6
3
𝑣𝑎𝑣𝑔 = 2 m/s
To find speed, calculate
the gradient
What is the instantaneous
speed at 5 seconds?
Describe the motion for
each interval

13. ASNMT: Motion Graphs
• Due Tues 24.5
PRACTICAL: Motion Down a Ramp
• Finish ‘Conclusion and Evaluation’ questions
• Application questions are optional
• Due tomorrow

14. time (s)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 1.0 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.2 2.4
100
80
60
40
20
0
time (s)
distance
(cm)
Distance vs. Time

15. time (s)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 1.0 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.2 2.4
60
50
40
30
20
10
0
time (s)
average
speed
(cm/s)
Average Speed vs. Time

16. time (s)
100
80
60
40
20
0
time (s)
distance
(m)
Distance vs. Time
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

17. time (s)
50
40
30
20
10
0
time (min)
distance
(m)
Distance vs. Time
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

18. time (s)
9
8
7
6
5
4
3
2
1
0
time (sec)
distance
(cm)
Distance vs. Time
0 1 2 3 4 5 6 7 8 9 10