5-FAC-03
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Contents
Outcomes
Specification References
- 1.5 interpret velocity-time graphs
- 1.6 determine acceleration from the gradient of a velocity-time graph
- 1.7 determine the distance travelled from the area between a velocity-time graph and the time axis.
- 1.16 describe the forces acting on falling objects and explain why falling objects reach a terminal velocity.
Starter
- Using a motion sensor and Making Velocity-time Graphs
- The pupils extend the exercise from the previous lesson but now try and produce velocity time graphs
Main Body of Lesson
- Using The Journey again have the pupils use the last column of the table to work out the instantaneous speed at each step of the train journey. They should do this in groups so that they share out the work between four. This should make this go a bit quicker. From this they make the connection between constant slope being constant speed and horizontal portions being zero speed. Hand out The Journey - sketching velocity-time graphs. This allows pupils to sketch the velocity time graph below the distance time graphs with the time scale in-line. They can use their calculations from earlier to help add values to the y-axis. You can spend time pointing out the key points (horizontal->zero gradient->zero speed, constant slope-> constant gradient-> constant speed, changing slope-> changing gradient-> changing speed-> acceleration, steeper slope-> larger gradient-> greater speed)
- Have the students work out the area of the By Train velocity-time graph. This may require some estimating. What does this represent? Hopefully they will make the connection that the area under a velocity-time graph is the distance travelled. Look back at the data. How far does the train travel? Have them look at the units when they multiply the velocity and the time axis. It is important for them to see that the time unit cancels and they are left with metres.
- Finish with two or three example questions. These start easy and lead into negative velocity and objects travelling back home.
- Extension- Have the pupils sketch a distance time for a bouncing ball. Have them then sketch a velocity time graph from that. Use a motion sensor to show the shape of each graph. It is important to understand the vector nature of velocity and link travelling in the opposite direction to negative velocity below the x-axis.
Plenary
- Sketch a velocity-time graph for a falling object. A person jumping out of a plane.
Sheet to do this with diagrams of a person to label forces on at each stage of the jump. This will show when the resultant force is greatest (at the beginning) and when it is balanced ( at terminal velocity both without the chute open and with it open. This also points out that the weight vector does not change but the air resistance vector changes in magnitude according to the speed or if the parachute is open.
Homework
Additional Information
Resources Required
Textbook References
- None
Website References
- None
Skills Addressed
Safety/Hazards
Risk Assessment
Notes
- None
