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Physics

Learn how to calculate speed, distance, and time in physics. Discover the concept of velocity and understand acceleration. Engage in hands-on activities and quizzes to reinforce your understanding.

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Physics

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  1. Physics Speed and Acceleration

  2. Distance, time and speed To work out the speed of an object you need to know: • the distance travelled; • how long it took to travel that distance.

  3. Calculating average speed total distance d average speed = total time s x t formula triangle Average speed is calculated using this equation:

  4. Speed experiment – instructions total distance average speed = total time 1. Time how long it takes you to run 100m. 2. Then calculate your average speed for the run. 3. Repeat the experiment for each member of your group. 4. What was the fastest average speed for your group?

  5. Speed formula triangle

  6. Speed experiment – results Name distance (m) time (s) average speed (m/s) 100 100 100 100 100 Conclusion The fastest member of the group with an average speed of ________ was __________.

  7. Speed calculation example d (distance in m) average speed (in m/s) = t (time in s) d 360m = 120s s x t A boy takes 120 seconds to travel from his home to the school, a distance of 360 m. Calculate his average speed in m/s = 3 m/s Cover the quantity to be calculated - s (speed)

  8. Speed calculation – changing units d s x t Question 2 A group set off from home and walk at an average speed of 2.6 m/s. How far would they travel in 1 minute? distance (m) = speed (m/s) x time (s) = 2.6 m/s x 60s = 156 m

  9. Speed calculation and changing units d d (distance in m) average speed (in m/s) = t (time in s) s x t 10,000 m = 1x60x60 3600 s A boy takes 1 hour to travel from his home to the cinema, a distance of 10 km. Calculate his average speed in m/s. = 2.8 m/s Cover the quantity to be calculated - s (speed)

  10. Using the Distance, Speed, Time triangle

  11. The correct answers

  12. Velocity Velocity is the speed in a certain direction. Example The velocity of a cheetah is 15 m/s east.

  13. Example What is the velocity (in m/s) of a girl who travels 1800m west from her house to her school if it takes her 10 minutes to get there? Velocity = speed in a direction Speed = distance / time = 1800m/ 600s = 3m/s west Answer = 3m/s west

  14. Try this next one… A dog runs 0.5km in an southerly direction. It takes her 500 seconds. What is her velocity?

  15. Car graphing activity – instructions This graphing experiment shows an animation of a car travelling along a straight road. 1. Copy the results table shown on the next slide and complete it as the movie is played. 2. Record the distance the car has travelled every five seconds. 3. Plot a graph of your results.

  16. Car graphing activity – results table layout Results table for distance/time graph

  17. Car graphing activity – animation

  18. Car graphing activity – results table Results table for distance/time graph

  19. Car graphing activity – results graph

  20. What distance has she travelled after 13 seconds? How long does it take the car to travel 600m? What is her average speed after 5 seconds? What is her average speed after 30 seconds?

  21. Car graphing activity – results graph analysis The speed of the car is changing – the graph is not flat. The slope of the graph is less steep as the car begins to slow down. The car has stopped. The graph is flat – the distance of the car from the start point is not changing. The graph is straight – there is no change in speed. The car is going fast but at a constant speed. The graph is straight in this part of the journey. The car is starting to move. The curve shows that the speed is changing. The curve is upwards as the car accelerates at the start of the journey.

  22. Acceleration Acceleration is the change in velocity per unit time. • Acceleration = • Final speed – starting speed • Time taken for the change It is measured in m/s/s

  23. Acceleration = Final speed – starting speed Time taken for the change • A man running for a bus speeds up from 1m/s to 5m/s in 2 seconds. What is his acceleration? = 5m/s – 1m/s 2s = 4m/s 2s = 2m/s/s

  24. Acceleration = Final speed – starting speed Time taken for the change • In 10 seconds a cheetah changes her speed from 5m/s to 10m/s. What is her acceleration? = 10m/s – 5m/s 10s = 5m/s 10s = 0.5 m/s/s

  25. Car graphing activity – results table layout Results table for speed/time graph

  26. Car graphing activity – animation

  27. Questions about this speed time graph.. What speed is the car travelling at after 22 seconds? Does the speed of the car change during the drive? How can you tell this from the graph? What is the acceleration of the car after 25 seconds? What is the acceleration of the car between 40 and 55 seconds?

  28. Question 3 The table shows the velocity of a car travelling in a particular direction on a straight road over the first ten seconds of the journey • Draw the graph • Use it to find • The velocity of the car after 7.5s • The time taken for the car to reach a velocity of 5m/s • The acceleration of the car on this journey

  29. Anagrams

  30. Multiple-choice quiz

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