# scalars and vectors

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• Created by: tia5sos
• Created on: 02-12-20 20:17
• scalars and vectors
• scalars are quantities with size only (magnitude)
• examples: speed, distance, time and mass
• vectors have both size (magnitude) and direction
• examples: velocity, displacement, force and acceleration
• distance and displacement are different things
• they both measure how far something has travelled but displacement also says which direction something has travelled in
• for example, you could say a car has travelled a distance of 10m, but it has a displacement of 10m north
• to measure the speed of an object, you only need to measure how fast it is going
• ... calculating/ measuring the direction is not important
• e.g. speed = 30mph
• velocity is a more useful measure of motion
• this is because it describes both the speed and direction
• e.g. velocity = 30mph due north
• quantities like speed and distance, that are only numbers, are called scalar quantities
• quantities like velocity and displacement, that have direction and speed, are vectors
• example
• 1.when we use vectors, we often talk about there being a positive and a negative direction
• 2. a car moving in one direction could have a velocity of 3m/s, but moving in the opposite direction it will have a velocity of -3m/s
• 3. in this example, the car has a speed of 3m/s in both directions, you can often pick a positive direction that makes the calculations easier