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IGCSE Physics

Viraj Rijal

*Speed, Velocity and Acceleration

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*Speed*Speed is a scalar

quantity (has no direction) and refers to how fast something is covering a given distance in a particular interval of time

Example:-

D= 100km

t= 2hrs

S=100km/2hrs

S=50km/hr

Formula:

SI unit for speed: m/sOther units: km/hr, mi/hr

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*Forms of SpeedInstantaneous speed:-

The Speed at any given instance in time

Uniform Speed:-

When a body is travelling equal distances in equal intervals of time.

Average Speed:-The average of all instantaneous speeds, or the total distance travelled in the total amount of time.

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*Velocity*Velocity is a vector

quantity (has a specific direction of travel) and is referred to as the rate of a body changing its position.

*Or otherwise, the distance covered by a body over a period of time in a specified direction.

SI unit for Velocity: m/s Other units: mi/hr, km/hr

Velocity is direction aware, and when calculated, the direction of travel has to be mentioned. Ex. 150m/s East

Formula

𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦=𝐷𝑖𝑠𝑝𝑙𝑎𝑐𝑒𝑚𝑒𝑛𝑡

𝑇𝑖𝑚𝑒

Velocity can also have a negative travel, showing that the body is moving in the opposite direction.

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*Uniform Velocity

*Just like uniform speed, uniform velocity is when to bodies travel equal distances in equal intervals of time, but with a specified direction.

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*Acceleration*Acceleration is a

vector quantity, which is defined as the rate at which an object changes its velocity.

*An object is accelerating or decelerating if it is changing its velocity.

Formula for Acceleration:-

u =initial velocityv=final velocityt=change in time

SI unit for Acceleration:

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*Constant Acceleration or Deceleration

*Constant acceleration or deceleration is defined by the change of velocity at a constant rate at any given time.

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*Graphs

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