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## Class 11 Physics (India)

### Course: Class 11 Physics (India)>Unit 6

Lesson 1: Distance, displacement, and coordinate systems

# Distance and displacement introduction

An introduction to the difference between distance traveled and displacement. Created by Sal Khan.

## Want to join the conversation?

• Would it be correct to say that displacement is the end-point, the last stop?
• Not exactly. Displacement is the shortest distance from your initial position to your final position. Therefore, displacement is a measurement of distance and not an "end-point."
• If the sheep traveled 10km east, 5km south, 10km west, and then 5km north will the displacement be 0?
• Yes, because the sheep will walk in a square, therefore, the starting position and ending position will be the same, so the displacement is zero because 0-0=0
• If it didn't go 10 km west, you would use the Pythagorean theorem, right
• pythagorean theorem is used only when the object turns about only in 90 degrees
• i did not understand the exact meaning of displacement?
• Displacement is the final distance of a point from the initial point.
For instance, if I walked 10 meters from my house, then walked 5 meters towards my house, my displacement from my house would have been 5 meters, even though I walked 15 meters in total.
Displacement is more of an a-to-b measure, rather than a how-did-a-get-to-b measure, if that makes more sense.
• Why would it not be correct to say that the sheep travelled -5 km south?
• What you are doing by saying -5 km south is giving the direction twice: the first time by denoting the "-" symbol before the five and a second time by saying "south." You want to use only one method of indicating direction.
This can be done by using a positive/negative symbol or by using a direction word such as north, up, down, west etc.
• From we can say that the * definition of displacement is "change in position" * and for * distance is "total length of path travelled" * ?
• Well yes we can that displacement refers to the change between the initial and final position and distance refers to the whole length of path covered by an object
• This might not be totally on topic, but...
I've noticed some people here in the comments mentioning the Pythagorean Theorem as a reference to the problems in this lesson. While I am familiar with the theorem itself, I have no idea how that would apply here.
Could somebody explain how you use the Pythagorean Theorem in physics?
Sorry if this is a silly question-this is my first time studying physics (and I'm lousy at math) :)
• You can use the pythagorean theorem to find the distance between any two points on a coordinate plane as part of the distance formula. People are just mentioning that if the sheep hadn't gone West you would've needed to use the distance formula to figure out the displacement of the sheep because it wouldn't have been immediately obvious.
• Did the sheep get its food at the end?
• hopefully it did.