Vectors and Scalars
Dynamics is, by definition, a branch of mechanics which focuses on the motion of bodies under the action of forces. To properly understand motion, forces and dynamics in physics, we must open with some definitions to get the ball rolling.
Scalars
Scalars are quantities that are fully described by its magnitude.
Examples:
Time
Mass
Energy
Speed
Distance
Volume
You may say: “This cup has a volume of 1L.” Therefore, volume is fully described by magnitude
Vectors
Vectors are quantities that are described by both magnitude and direction.
Examples:
Velocity
Displacement
Force
Acceleration
Momentum
You may say: “The car is travelling on the motorway at a velocity of 20m/s, travelling due-East.” So we require a direction to be added to vectors to fully understand the quantity, which in this case is velocity.
Key Points!
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Vectors and Scalars
You need to be able to understand and define the difference between vectors and scalars, as well as provide examples of the two.
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Resultant Vectors
Calculating resultant vectors is a very common exam question which requires multiple steps.
Easy marks can be picked up here by practicing calculating resultant vectors.
Use Pythagoras and SOHCAHTOA to calculate vectors mathematically.
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Displacement, Velocity, Time
Understanding s = vt and being able to rearrange this equation will help further on in this unit.
On velocity-time graphs:
Gradient is acceleration
Area under the graph is displacement