Chapter 7
S EC T I O N 3
GRAVITY
A N O N CO N TAC T F O R C E
We will learn about force field,
centre of mass and terminal
velocity.
Force Field
Gravitational field lines are always
towards the centre. Why?
Mass is spread throughout an object but can be
thought of as being concentrated in a point called
its
centre of mass.
To keep an object in balance centre
of mass must lie through its base
Freefall in the vacuum
Which one hits the ground
first?
Why, then?
The greater the surface area,
the more air friction applies ,
the slower the objects falls.
Felix the skydiver
Lets show forces acting on the parachutist and predicts his motion…
the forces acting on the object are balanced and the object then falls at a constant
speed.
This speed is called terminal velocity