Chapter 2 Forces and Motion

2.2 Analysing Motion Graph

There are two main types of linear motion graphs

1.Displacement – Time graph2.Velocity – Time graph

2.2 Analysing Motion Graph

http://www.youtube.com/watch?v=x2ve5yucNPQ

02:30

2.2 Analysing Motion Graph

2.2 Analysing Motion GraphDisplacement – Time graph

2.2 Analysing Motion GraphDisplacement – Time graph

Gradient of the graph = velocity of the

object

2.2 Analysing Motion GraphDisplacement – Time graph

1-s m 0.5s 200m 100

Gradient

Isection For

xy

For section II, gradient = 0, which means the velocity at this moment is zero.

1-s m 0.5s 200m 100

Gradient

IIIsection For

xy

The negative sign shows the direction ofThe motion is opposite to the original direction. (Velocity is a vector quantity)

2.2 Analysing Motion GraphDisplacement – Time graph

2.2 Analysing Motion GraphDisplacement – Time graph

2.2 Analysing Motion GraphDisplacement – Time graph

2.2 Analysing Motion GraphDisplacement – Time graph

2.2 Analysing Motion GraphDisplacement – Time graph

A particle starts to move to the north at time, t=0 s. The displacement-time graph above shows the particle moving from its original position from a tree.

(a) What is the displacement of the particle from the tree at the start

of its motion?(b) What is the velocity of the particle from t = 2 s to t = 6 s?(c) For how long did the particle move southwards?(d) At what time did the particle pass the position of the tree?

2.2 Analysing Motion GraphDisplacement – Time graph

2.2 Analysing Motion GraphVelocity – Time graph

60 m/s

2.2 Analysing Motion GraphVelocity – Time graph

Gradient of the graph = acceleration of

the object

2.2 Analysing Motion GraphVelocity – Time graph

For section II, gradient = 0, which means the car travels at a constant velocity from 20 s to 40 s.

The negative sign indicates a deceleration.

2-

1-

s m 3s 20

s m )060(

Gradient

Isection For

xy

2-

1-

s m 3s 20

s m )600(

Gradient

IIIsection For

xy

2.2 Analysing Motion GraphVelocity – Time graph

Area under the graph = distance travelled

2.2 Analysing Motion GraphVelocity – Time graph

2.2 Analysing Motion GraphVelocity – Time graph

2.2 Analysing Motion GraphVelocity – Time graph

2.2 Analysing Motion Graph

http://physics.info/motion-graphs/

2.2 Analysing Motion GraphVelocity – Time graph

2.2 Analysing Motion GraphVelocity – Time graph

2.2 Analysing Motion Graph

2.2 Analysing Motion Graph

2.2 Analysing Motion Graph

The moving man