Velocity versus time form acceleration versus time

AI Thread Summary
To create a velocity versus time (v vs t) graph from an acceleration versus time (a vs t) graph, the area under the a vs t graph must be calculated. Since the acceleration data is discrete, integration can be approximated by summing the products of acceleration and the time interval (0.1 s). The formula v_n = v_{n-1} + a_n(0.1) is used to find the velocity at each time point. For position, the equation x_n = x_{n-1} + v_{n-1}(0.1) + (0.5)a_n(0.1)^2 is suggested, although an alternative kinematic equation may provide better results. This method allows for accurate tracking of velocity and position over time.
KillerZ
Messages
116
Reaction score
0

Homework Statement



I have some data from a lab conducted with a accelerometer to collect the acceleration and I am trying to figure out how to create a v vs t graph from the a vs t graph. When I create the a vs t graph in excel its very crazy looking because of the change in acceleration at every 0.1 s from 0 s to 79.6 s. I know the v vs t is constructed from the area under the a vs t graph. The speed of the object is 0 km/h to 40 km/h = 0 m/s to 11.1111 m/s. I have every point of the instantaneous acceleration at every 0.1 s.

my a vs t graph:
14tydsj.png


my acceleration data looks like this from 0 s to 79.6 s:
avsz1s.jpg


Homework Equations



\Delta v = \int a dt

The Attempt at a Solution



well I know the time is 0 s to 79.6 s and the velocity is 0 m/s to 11.1111 m/s so I think I can integrate?

\Delta v = \int a dt
 
Physics news on Phys.org
Integration is actually a discrete sum in this case. You don't have an analytical function that you can integrate. Just multiply the acceleration at a given point in time by the time interval Δt = 0.1 s and call that Δv. Add all the Δv's from time zero to the time of interest to get the velocity at the time of interest.
 
I used this formula:

v_{n} = v_{n-1} + a_{n}(0.1)

which is what you said but would the position be:

x_{n} = x_{n-1} + v_{n-1}(0.1) + (0.5)a_{n}(0.1)^{2}

y_{n} = y_{n-1} + v_{n-1}(0.1) + (0.5)a_{n}(0.1)^{2}

for every point?
 
It will (probably) be better to use the "other kinematic equation"

<br /> \Delta x_{n} = \frac{v_{n}^2-v_{n-1}^2}{2a_{n}}<br />
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top