Why do we use area under the curve to find displacement in particle motion?

In summary, the conversation discusses calculating the distance traveled by a particle with given velocity and position data. It is mentioned that the total distance can be found by subtracting the reverse distance traveled from the original distance. Another method suggested is to find the area under the curve of speed vs. time. This is equivalent to finding the distance covered by the particle. The concept of finding the area under the curve is used because it represents the distance traveled, and in this case, it is easier since there are two right triangles to consider.
  • #1
rudransh verma
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Homework Statement
The displacement of a particle moving in straight line is given by ##s=6+12t-2t^2##. The distance covered by particle in first 5sec. Units are in meters and sec.
Relevant Equations
##v=\frac{ds}{dt}##
I calculated v=0 at t=3. s(3) =24 m. s(5)=16 m. So reverse distance that the particle travelled=24-16=8 m. So total distance =24+8=32 m.
 
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  • #2
But s=6 at t=0. Did you take this into account?
 
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  • #3
phyzguy said:
But s=6 at t=0. Did you take this into account?
O yes! I thought the position is origin at t=0. So it will be 32-6=26 meters. Thanks. Is there any other way to do it ?
 
  • #4
Well, you could take the velocity, which is v = ds/dt = 12 - 4t, and then find [itex]\int_0^5 |v| dt = 26 [/itex].
 
  • #5
rudransh verma said:
Is there any other way to do it ?
You can also plot speed vs. time and find the area under the curve (see below) which is easy in this case of two right triangles. This is the geometric equivalent of what @phyzguy suggested in post #4.

Vee_vs_Tee_2.png
 
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  • #6
kuruman said:
You can also plot speed vs. time and find the area under the curve
Ok! By the way why we use area under the curve thing.
Is it because finding area under the curve (integral) give the distance covered and we use the same concept of finding the area except it’s easy here because there are two triangles?
 
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  • #7
rudransh verma said:
Ok! By the way why we use area under the curve thing.
Is it because finding area under the curve (integral) give the distance covered and we use the same concept of finding the area except it’s easy here because there are two triangles?
Yes.
 

1. Why is area under the curve used to find displacement in particle motion?

The area under the curve represents the distance traveled by a particle over a certain period of time. This is because the curve is a graphical representation of the particle's velocity, and the area under the curve is equal to the product of velocity and time, which gives us the displacement.

2. Can't we just use the final position minus the initial position to find displacement?

In some cases, this method may work. However, it assumes that the particle is moving at a constant velocity, which is not always the case. Using the area under the curve method takes into account any changes in velocity and provides a more accurate measurement of displacement.

3. How does the shape of the curve affect the displacement calculation?

The shape of the curve directly affects the displacement calculation because it determines the velocity of the particle at any given time. A steeper curve indicates a higher velocity, while a flatter curve indicates a lower velocity. This variation in velocity is taken into account when calculating the area under the curve.

4. Is the area under the curve always positive?

No, the area under the curve can be positive or negative, depending on the direction of the particle's motion. If the particle is moving in a positive direction, the area under the curve will be positive. If the particle is moving in a negative direction, the area under the curve will be negative.

5. Can the area under the curve be used to find other quantities besides displacement?

Yes, the area under the curve can also be used to find other quantities such as velocity and acceleration. By taking the derivative of the curve, we can find the slope at any point, which represents the instantaneous velocity. And by taking the second derivative, we can find the rate of change of velocity, which represents the acceleration.

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