Find Velocity when Acceleration Vs Time Graph

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SUMMARY

The discussion focuses on calculating the velocity of a particle at 7 seconds using an acceleration versus time graph. The user attempts to integrate the acceleration values over specified intervals, specifically from 0 to 5 seconds, resulting in a total area of -50. The conversation emphasizes the importance of understanding the concept of area under the curve, particularly distinguishing between positive and negative areas, to accurately determine the velocity. The user expresses confusion about how to handle areas above and below the axis, indicating a need for clarity on integration techniques in this context.

PREREQUISITES
  • Understanding of integration techniques in calculus
  • Familiarity with acceleration versus time graphs
  • Knowledge of how to calculate area under a curve
  • Basic concepts of positive and negative areas in physics
NEXT STEPS
  • Study the concept of area under the curve in integration
  • Learn how to differentiate between positive and negative areas in physics
  • Explore integration of piecewise functions for varying acceleration
  • Review the relationship between acceleration, velocity, and displacement
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Students studying physics or calculus, particularly those focusing on kinematics and integration techniques, as well as educators looking for examples of real-world applications of these concepts.

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Homework Statement


Find the particles Velocity at 7 seconds . ( Graph Below)

attachment.php?attachmentid=43187&stc=1&d=1327701197.jpg

Homework Equations


attachment.php?attachmentid=43188&stc=1&d=1327701250.jpg


The Attempt at a Solution



T=5 from 7-2
or
T=2 From 7-5 ( Because It's now -a)

I tried int from 0 to 5 -10dt and got -50
then AT=v with both
A @ 7 second = (-20*2)/2 = -20

Is velocity not negative.
I am really embarrassed to ask for help. I would love to understand , and maybe remind me some how science is fun ..
 

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I will assume you are familiar with differentiation since it's listed under relavant equations. Do you know integration yet? If not, think about the graph of a constant acceleration - how do you find the velocity of a constant acceleration versus time graph?
 
Yes , I am comfortable with doing integration.

In this case I am not sure what is area. I know that area is from t 0 - 5 is on the positive side . I am not sure if I should add the two areas to find the v at 7s or something else.

I haven't had I chance to talk about negative area to so it's just a bunch of assumitions , which I don't like.

So , Should I find the area of the partial triangle then the other one below axis ?

Or something else ?
 
If I just do are both on the positive side and negative side of the a axis i get the quantities

20 ( t , 1-2 ; up tri )
20 (t 1-2 ; below rectangle )
45 (t 2-5 ; large tri )
20 ( t 5-7 ; tri in 4 quadrant ) ( is this positive or negative area )
 
Last edited:
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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