Summary of IEB Physical Sciences Physics

Physics Notes
Kinematics
Displacement, Velocity, Acceleration

1. Frame of reference
a. This is a reference point from which other objects are observed.
2. One dimensional motion
a. This is when an object is contained back and forth along a line.

Position

1. Position is a measurement of location with reference to an origin.
2. Quantity symbol 𝑥
3. SI unit (m)
4. Position is a vector quantity that points from the reference point.

Distance

1. Distance is the length of path travelled.
2. Distance is a scalar.
3. SI unit (m)

Displacement

1. Displacement is the change in position of an object.
2. It is vector quantity that prints from the Xi to the Xf.
3. Quantity symbol: 𝛥𝑥

Differences between distance and displacement.

Distance Displacement
Depends on the path Independent of the path
Always positive Can be positive or negative
Is a scalar Is a vector


Speed

1. Speed is the distance (D) travelled divided by the time 𝛥𝑡 taken for the journey.
2. Quantity symbol – V (same as velocity)
𝐷
3. 𝑉 = 𝛥𝑡
4. SI unit – m/s or m.s-1

Velocity

1. Velocity is the rate of displacement.
𝛥𝑥
2. 𝑉 =
𝛥𝑦
3. SI unit m/s or m.s-1




1

,Average velocity
𝑣𝑖 +𝑣𝑓
1. 𝑉𝑎𝑟 = 2

Instantaneous velocity

1. Velocity at a particular point.

Acceleration

1. Acceleration is the rate of change of velocity.
𝛥𝑣
2. 𝑎 = 𝛥𝑡

Graphs of motion

1. Position time graph (acceleration = 0)




a. Gradient = velocity
b. Gradient/velocity is constant.
2. Position time graph (acceleration > 0)




a. Gradient/velocity is increasing.
b. Instantaneous velocity at any time is equal to the tangent of a point.




2

, 3. Position time graph (acceleration < 0)




a. Gradient/velocity is decreasing.
b. *
4. Velocity time graph (acceleration = 0)




a. Body remains at constant velocity.
b. Gradient/acceleration is 0.
5. Velocity time graph (acceleration > 0)




a. Velocity is increasing.

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