Transcript Circular motion and Orbits - Lesson 1

Circular Motion and Orbits
Lesson 1: How Can You Move In A Circle?
Dodgems
• What forces act on Dodgems?
– What causes them to stop, speed up, slow down,
change direction?
Dodgem Card Sort
• Divide the forces in your card sort into three
categories
– Forces which speed you up
– Forces which slow you down
– Forces which change direction of motion
Today’s Lesson
• How can you move in a circle?
– What do you expect to know by the end of the
lesson?
Circular Motion – developing ideas
• An object moving in a circle
changes direction all the time
• When an object changes
direction, it is due to a resultant
force (Newton’s 2nd Law)
• This force acts towards the
centre of the circle
• The force has a special name
centripetal force
• The object is said to accelerate
towards the centre of the circle
(centripetal acceleration)
The Rubber Bung Experiment
SAFETY
• See worksheet
Wear Eye
Protection
Plastic tube
Rubber bung
eye
Marker
Masses
What have you learnt?
• Arrange the following into six sentences about
circular motion
This force is called a
Circular Motion requires a
As the radius of orbit increases,
Centripetal Force.
In our experiment, the
tension in the string
the centripetal force
As the speed of orbit increases,
As the mass of the orbiting
object increases,
Decreases.
the centripetal force
Increases.
Increases.
provides the centripetal force
needed.
force acting inwards towards the
centre of the circle.
the centripetal force
Homework
• Present your data in a table
• Present your data on a graph
• You will assess each other for
– Accuracy
– Reliability
– Quality of table
– Quality of graph