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## Mechanics (Essentials) - Class 11th

### Course: Mechanics (Essentials) - Class 11th>Unit 4

Lesson 2: Turning a race into a snapshot

# Worked example: distance and displacement from position-time graphs

Worked examples finding displacement and distance from position-time graphs.

## Want to join the conversation?

• It's so confusing for me especially to calculate the distance. The one that I learn in school to calculate the distance is to multiply the speed by the time. But this one is so confusing I can't figure it out.
• Just add the absolute values of all the travelling. Suppose Tony Stark moved forwards 5m, move backwards 8m, and then moves forward 12m. Abs=absolute value
Distance:
Abs(5)+abs(-8)+abs( 12)
5+8+12
25
Tony Stark traveled a DISTANCE of 25m
• sorry i thought the distance traveled by the armadillo will be 30km
can you explain more?
• at rest the roll was 6m , so we are not taking 6 while calculating the distance. basically it STARTED FROM 6m, then travelled 9m n then travelled 15m south
the roll went from 6m to 15m so it travelled 9m and then from 15m it went down to 0 so it travelled 15 m. hence the answer = 9+15 = 24m

hope this helps!
• this is so confusing
• Isn't distance is the magnitude of displacement?
• Well actually, distance is only equal to the magnitude of displacement when the direction doesn't change, but like the guy says in the video at around , the negative sign on that 6 signifies a different direction than that positive 9. And due to the fact that the direction changed, the distance can't be equal to the magnitude of displacement.
• he said zero minus negative two is two at and zero minus six is negative six at and now I'm confused Someone help me or am I overthinking this I don't knoww
• Not to be insulting, but if that's confusing, you should go back and do some basic maths first so you can understand this. Physics is built straight from mathematics.

zero minus negative two looks like this: 0-(-2)=2
Thats getting rid of 2 negative twos, or adding 2
zero minus six equals negative six looks like this: 0-6=-6
This is subtracting or getting rid of six
• What does it mean by horizontal position?
• That is your displacement along the "x" axis. For example, x=7 would typically be 7 meters to the right of zero or the starting position and x=-3 would be 3 meters to the left of zero or the starting position.
• Sorry if this is stupid but,
What was the difference between distance and displacement?
(1 vote)
• Hello HyperDraco, well to answer you question about the difference between distance and displacement, it is that displacement does not matter on how much your "total" steps were taken but rather what was the end results of your steps "compared to you initial start." While distance only cares about how much you traveled and not where you ended up in relation to where you started. You can think about displacement and distance as two professors, one that values you based on your improvement (most improved or results-based professors, aka displacement) and the other professor is the one who only cares about your effort given and not where you ended up (aka how much work you did which is like distance: your total amount traveled). Xf-Xi=displacement which is change in X.
• Why put the weight of the animals? Isn't it redundant?