Difference between revisions of "5-DFAC-01"
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* Going back to '''The Journey''' hand out, ask the pupils in what portion is the train accelerating? decelerating? How do they know? What is acceleration? How would it be measured? The key is for them to understand that the change in speed is need and the time for that change. How can a light gate measure acceleration? Introduce them to a double interrupter. Write the formula for acceleration on the board. Use the symbol v and u for final and initial speed. Write the formula again but sub in the speed formula for v and u. What time does the computer use to find the speed? What time does the computer use to find the acceleration? Go onto the picket fence again. Try this with the trolley and the ramp. Measure the cars acceleration. Show them how this is done on Data Studio. Will the acceleration be different if the ramp is tipped more? | * Going back to '''The Journey''' hand out, ask the pupils in what portion is the train accelerating? decelerating? How do they know? What is acceleration? How would it be measured? The key is for them to understand that the change in speed is need and the time for that change. How can a light gate measure acceleration? Introduce them to a double interrupter. Write the formula for acceleration on the board. Use the symbol v and u for final and initial speed. Write the formula again but sub in the speed formula for v and u. What time does the computer use to find the speed? What time does the computer use to find the acceleration? Go onto the picket fence again. Try this with the trolley and the ramp. Measure the cars acceleration. Show them how this is done on Data Studio. Will the acceleration be different if the ramp is tipped more? | ||
*Show the pupils how three readings of acceleration can be obtained very quickly by releasing and catching the trolley just after it passes through the gate. | *Show the pupils how three readings of acceleration can be obtained very quickly by releasing and catching the trolley just after it passes through the gate. | ||
| − | * They will be measuring the acceleration in the next lesson and they need to be comfortable with the program and understand the need to take three quick successive readings | + | * They will be measuring the acceleration in the next lesson and they need to be comfortable with the program and understand the need to take three quick successive readings for each force or mass. |
| − | + | ||
==Plenary== | ==Plenary== | ||
Revision as of 16:56, 31 August 2010
Contents
Outcomes
- Pupils should be able to recall and use the relationship:
<math>avg speed = distance moved/time taken</math>
- They should appreciate the difference between average speed and instantaneous speed.
- Pupils should know how to measure average speed practically including an understanding of how a light gate measures velocity.
- Pupils should be able to recall and use the relationship:
<math>a = (v - u)/ t</math>
- Pupils should have an appreciation for how a light gate measures acceleration using a double interrupter or a picket fence.
Specification References
- 1.3 recall and use the relationship between average speed, distance moved and time:
<math>avg speed = distance moved/time taken</math>
- 1.4 recall and use the relationship between acceleration, velocity and time:
<math>a = (v - u)/ t</math>
Starter
- Brain storm: What is speed? What is velocity? What is the difference between them? Revise vector and scalars.
- Discuss how the speed of car can be measured. What equipment would one need?
- Lead into the formula or hopefully have the class come up with the formula and the fact that distance and time are needed.
- Hand out a copy of The Journey, which includes data for two journeys From Reigate to Redhill. One by train and the other by bus. The train is going directly to the destination without stopping and the bus is required to stop several times to pick up other passengers. The questions require them to assess each journey. They begin by working out the speed in several portions of each journey. They end by calculating the average speed for each mode of transport and the overall average speed of each journey. The bus requires some walking either end to get to or from the stations and is included in the data. This will allow them to appreciate the meaning of average speed and instantaneous speed. This can be extended by drawing distance-time graphs. Their are copies of the distance-time graphs already produced on the shared drive.
- What is the difference between average speed and instantaneous speed?
Main Body of Lesson
Using The Light Gate
- Run a trolley down a ramp (without an interrupter) and through a light gate. Ask the pupils how a light gate measures the speed of the trolley. Passing your hand through the light beam slowly and then quickly may help them to understand that the time will be measured in that way. Hold up an interrupter. Pass it through the light gate. What does the computer need to calculate the speed? Have a pupil measure the width of the single card. Enter that into the program and take several readings of the speed of the trolley down the ramp. Try a different size interrupter if there is time. Have a pupil enter its width. Show them once again how the speed is obtained in Data Studio. Hold up the picket fence. Ask them how this works.
- Going back to The Journey hand out, ask the pupils in what portion is the train accelerating? decelerating? How do they know? What is acceleration? How would it be measured? The key is for them to understand that the change in speed is need and the time for that change. How can a light gate measure acceleration? Introduce them to a double interrupter. Write the formula for acceleration on the board. Use the symbol v and u for final and initial speed. Write the formula again but sub in the speed formula for v and u. What time does the computer use to find the speed? What time does the computer use to find the acceleration? Go onto the picket fence again. Try this with the trolley and the ramp. Measure the cars acceleration. Show them how this is done on Data Studio. Will the acceleration be different if the ramp is tipped more?
- Show the pupils how three readings of acceleration can be obtained very quickly by releasing and catching the trolley just after it passes through the gate.
- They will be measuring the acceleration in the next lesson and they need to be comfortable with the program and understand the need to take three quick successive readings for each force or mass.
Plenary
- Using the formulae - This time can be spent practising the use of the two formula. Here is a Formula Powerpoint with some questions for them to try and here is a sheet with the Formula questions so that they do not need to copy the questions down. This should set them up nicely to complete their homework.
Homework
- Speed and Acceleration Question Sheet
Additional Information
Resources Required
Textbook References
- None
Website References
- None
Skills Addressed
Safety/Hazards
Notes
- None
