Help with Displacement vs. time and acceleration

In summary, the conversation discusses a quadratic regression for a displacement vs. time graph of a ball being dropped from rest. The regression equation is given and the R^2 value is mentioned. There is also mention of the kinematic equation and the need to make a velocity vs. time graph using this information. The conversation concludes with a suggestion to redo the regression with the constraint that the ball was dropped from rest.
  • #1
lmn
1
0

Homework Statement



I have the following points that were gathered from a displacement vs. time graph (the graph is of a ball being dropped from rest). The line is parabolic. The quadratic regression for the points is [tex]-4.03x^2-2.06x+1.20[/tex] where [tex]R^2=0.99857[/tex].

Correct me if I'm wrong but the quadratic regression is the same as this: [tex]h(t)= \frac {1}{2}At^2+V_{0}t+h_{0}[/tex]

I need to make a velocity vs. time graph with this information but I need a little guidance.

(time (s), displacement (m))
(0.000, 1.194)
(0.097, 0.979)
(0.129, 0.881)
(0.161, 0.774)
(0.193, 0.654)
(0.258, 0.399)
(0.290, 0.254)
(0.322, 0.102)
(0.354, 0.000)


Homework Equations


[tex]h(t)= \frac {1}{2}At^2+V_{0}t+h_{0}[/tex]


The Attempt at a Solution


I performed the quadratic regression but now I'm stuck
 
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  • #2
Think of x as representing time t, then match whatever constants you found from your quadratic regression to the constants in the kinematic equation that you quoted. But (and this is a big "but") if the ball was dropped from rest, then the linear term in t must have its coefficient constrained to be zero for a meaningful fit (i.e. v0=0). I think you need to redo your regression with that in mind. You should be able to predict from the kinematic equation what the fitted parameters ought to be and then verify that they are what you expected.
 
  • #3
on how to use this information to create a velocity vs. time graph.

Great job on performing the quadratic regression and obtaining a high R^2 value! This indicates that the quadratic equation is a good fit for the data points and can be used to accurately describe the motion of the ball.

To create a velocity vs. time graph, you will first need to find the velocity at each time point. This can be done by taking the derivative of the displacement vs. time equation, which will give you the velocity vs. time equation: v(t) = At + V0.

Next, you can plug in the time values from the given data points into the velocity equation to calculate the corresponding velocities. Once you have these values, you can plot them on a velocity vs. time graph.

Keep in mind that the velocity vs. time graph will also be parabolic, as the velocity is changing at a constant rate due to the acceleration of gravity. The graph will start at V0 (initial velocity) and decrease as the ball accelerates towards the ground.

I hope this helps guide you in creating your velocity vs. time graph. Remember to always double check your calculations and make sure they make sense in the context of the problem. Good luck with your homework!
 

1. What is displacement vs. time?

Displacement vs. time is a graph that shows the change in position (displacement) of an object over a specific time period. It is used to visually represent the motion of an object and can provide information about its speed and direction.

2. How do you calculate displacement vs. time?

To calculate displacement vs. time, you need to know the initial position and the final position of the object. Subtract the initial position from the final position to get the displacement. Then, divide the displacement by the time taken to get the average velocity over that time period.

3. What is the difference between displacement and distance?

Displacement is a vector quantity that refers to the shortest distance between the initial and final position of an object. Distance, on the other hand, is a scalar quantity that refers to the total length of the path traveled by an object. Displacement takes into account the direction of motion, while distance does not.

4. How does acceleration affect displacement vs. time?

Acceleration is the rate of change of an object's velocity. It affects displacement vs. time by determining the slope of the graph. A positive acceleration results in an upward slope, indicating an increase in displacement over time. A negative acceleration results in a downward slope, indicating a decrease in displacement over time.

5. What can we learn from a displacement vs. time graph?

A displacement vs. time graph can tell us about the motion of an object, including its speed, direction, and changes in velocity. It can also help us calculate other motion-related quantities such as acceleration and average velocity. Additionally, it can show if an object is at rest, moving at a constant speed, or accelerating.

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