Additional Physics – Forces

L/O :- To know why a falling object reaches terminal velocity

“The physics of falling”

Exam Date -

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

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

What are the forces acting on this

skydiver?

What happens to these forces as the

skydiver falls faster?

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 . . .

Do you think, what an object falls through will affect it’s speed?

Hypothesis

Prediction

Independent variable =

Dependent variable =

Control variables

Repeatability

What will your table look like?

Speed (m/s)1 2 3 Repeat Average

Fluid Time taken to fall (s) 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?

So which graph matches which liquid

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?