1. Additional Physics – Forces
Exam Date -
“The physics of falling”
L/O :- To know why a falling object reaches terminal velocity

2. Quick quiz
What can the motion be like of an object with BALANCED forces? (2 marks)
What can the motion be like of an object with UNBALANCED forces (2 marks)
How do you work out speed?
What 2 equations can you use to work out acceleration?
What is acceleration measured in?
What 2 things affect stopping distance?
Name 3 things that affect thinking distance
Name 3 things that affect braking distance

3. Explain what can affect the breaking distance of a car, and how drivers can help to prevent these factors being a problem? 6 marks
Weather – rain and ice etc. 
These an reduce the friction and increase the braking distance. 
Drivers should slow down and leave more space between cars 
Condition of tyres 
Less tread on the tyres will reduce friction and increase braking distance 
Yearly MOT’s check the tread on the tyres 
Speed 
Increased speed increases stopping distances 
Following the speed limit should ensure drivers have enough distance to stop in an emergency 

4. What are the forces acting on this skydiver?
When the skydiver first jumps out of the plane he accelerates quickly this is because . . .
Eventually the skydiver will reach a constant speed called terminal velocity. This happens because . . .
What happens to these forces as the skydiver falls faster?

5. Do you think, what an object falls through will affect it’s speed?
Hypothesis
Prediction
Independent variable =
Dependent variable =
Control variables
Repeatability

6. Will this affect the terminal velocity?
What will your table look like?
Fluid
Time taken to fall (s)
Speed
(m/s) 1 2 3
Repeat
Average
Speed
(m/s) 1 2 3
Repeat
Average
What do your results tell you?
How does the fluid affect the speed of the object?
Explain this using your knowledge of forces
Will this affect the terminal velocity?

7. So which graph matches which liquid

9. What have you learnt? Do you know what terminal velocity is?
Do you know what the forces are like on an object when it has reached terminal velocity?