Infinity Question (some physics background)

PatrickDinehart

New Member
Joined
Sep 3, 2014
Messages
3
I have a noobish question but I haven't been able to figure it out. In physics, we did a design lab (make a lab up on the spot and do it) and I was trying to calculate the correlation between the angle of a ramp to the acceleration of a car that went down the ramp. Of course, we are at the beginning of the year so we're limited to simple kinematics and derivatives/integrals. At a ramp of 0 degrees, the time for the car to go down it is infinite and thus, the acceleration would be calculated under the following premises:

X=x0 + vot + (1/2)a(t^2)

To make this plug able into Excel, I moved a (acceleration) to one side of the equation and plugged in x, x0, v0, and t. The problem here is t is infinite. For reference, the equation ended up being: =0.5*((0+0*(C8)+(C8^2))/1.0385) where C8 is the AVG Time (5 trials 5 times ect).

Is it possible I have used the wrong infinity symbol or is this simply incalculable?

Thanks in advance,
Patrick
 

Excel Facts

Bring active cell back into view
Start at A1 and select to A9999 while writing a formula, you can't see A1 anymore. Press Ctrl+Backspace to bring active cell into view.
The car doesn't take an infinite amount of time to go down the ramp when the slope is zero; the time increases without limit ('approaches infinity') as the slope of the ramp decreases toward zero:

Programming languages don't know about infinity.
 
Last edited:
Upvote 0
The acceleration of the car is the acceleration of gravity times the sine of the slope:

[Table="width:, class:grid"][tr][td] [/td][td]
A​
[/td][td]
B​
[/td][td]
C​
[/td][td]
D​
[/td][/tr]
[tr][td]
1​
[/td][td]
Slope [deg]​
[/td][td]
-5​
[/td][td][/td][td]B1: Input[/td][/tr]

[tr][td]
2​
[/td][td]
accel [m/s/s]​
[/td][td]
-0.854​
[/td][td][/td][td]B2: =9.8*SIN(RADIANS(B1))[/td][/tr]

[tr][td]
3​
[/td][td][/td][td][/td][td][/td][td][/td][/tr]

[tr][td]
4​
[/td][td][/td][td]
v0 [m/s]​
[/td][td]
x0 [m/s]​
[/td][td][/td][/tr]

[tr][td]
5​
[/td][td][/td][td]
0​
[/td][td]
0​
[/td][td][/td][/tr]

[tr][td]
6​
[/td][td]
t​
[/td][td]
v [m/s]​
[/td][td]
x [m]​
[/td][td][/td][/tr]

[tr][td]
7​
[/td][td]
0​
[/td][td]
0.00​
[/td][td]
0.00​
[/td][td]B7: =$B$2*A7[/td][/tr]

[tr][td]
8​
[/td][td]
1​
[/td][td]
-0.85​
[/td][td]
-0.43​
[/td][td]C7: =$C$5 + $B$5*A7 + $B$2*A7^2/2[/td][/tr]

[tr][td]
9​
[/td][td]
2​
[/td][td]
-1.71​
[/td][td]
-1.71​
[/td][td][/td][/tr]

[tr][td]
10​
[/td][td]
3​
[/td][td]
-2.56​
[/td][td]
-3.84​
[/td][td][/td][/tr]

[tr][td]
11​
[/td][td]
4​
[/td][td]
-3.42​
[/td][td]
-6.83​
[/td][td][/td][/tr]

[tr][td]
12​
[/td][td]
5​
[/td][td]
-4.27​
[/td][td]
-10.68​
[/td][td][/td][/tr]

[tr][td]
13​
[/td][td]
6​
[/td][td]
-5.12​
[/td][td]
-15.37​
[/td][td][/td][/tr]

[tr][td]
14​
[/td][td]
7​
[/td][td]
-5.98​
[/td][td]
-20.93​
[/td][td][/td][/tr]

[tr][td]
15​
[/td][td]
8​
[/td][td]
-6.83​
[/td][td]
-27.33​
[/td][td][/td][/tr]
[/table]
 
Upvote 0
The acceleration of the car is the acceleration of gravity times the sine of the slope:

[TABLE="class: grid"]
<tbody>[TR]
[TD][/TD]
[TD]
A​
[/TD]
[TD]
B​
[/TD]
[TD]
C​
[/TD]
[TD]
D​
[/TD]
[/TR]
[TR]
[TD]
1​
[/TD]
[TD]
Slope [deg]​
[/TD]
[TD]
-5​
[/TD]
[TD][/TD]
[TD]B1: Input[/TD]
[/TR]
[TR]
[TD]
2​
[/TD]
[TD]
accel [m/s/s]​
[/TD]
[TD]
-0.854​
[/TD]
[TD][/TD]
[TD]B2: =9.8*SIN(RADIANS(B1))[/TD]
[/TR]
[TR]
[TD]
3​
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]
4​
[/TD]
[TD][/TD]
[TD]
v0 [m/s]​
[/TD]
[TD]
x0 [m/s]​
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]
5​
[/TD]
[TD][/TD]
[TD]
0​
[/TD]
[TD]
0​
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]
6​
[/TD]
[TD]
t​

[/TD]
[TD]
v [m/s]​
[/TD]
[TD]
x [m]​
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]
7​
[/TD]
[TD]
0​
[/TD]
[TD]
0.00​
[/TD]
[TD]
0.00​
[/TD]
[TD]B7: =$B$2*A7[/TD]
[/TR]
[TR]
[TD]
8​
[/TD]
[TD]
1​
[/TD]
[TD]
-0.85​
[/TD]
[TD]
-0.43​
[/TD]
[TD]C7: =$C$5 + $B$5*A7 + $B$2*A7^2/2[/TD]
[/TR]
[TR]
[TD]
9​
[/TD]
[TD]
2​
[/TD]
[TD]
-1.71​
[/TD]
[TD]
-1.71​
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]
10​
[/TD]
[TD]
3​
[/TD]
[TD]
-2.56​
[/TD]
[TD]
-3.84​
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]
11​
[/TD]
[TD]
4​
[/TD]
[TD]
-3.42​
[/TD]
[TD]
-6.83​
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]
12​
[/TD]
[TD]
5​
[/TD]
[TD]
-4.27​
[/TD]
[TD]
-10.68​
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]
13​
[/TD]
[TD]
6​
[/TD]
[TD]
-5.12​
[/TD]
[TD]
-15.37​
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]
14​
[/TD]
[TD]
7​
[/TD]
[TD]
-5.98​
[/TD]
[TD]
-20.93​
[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]
15​
[/TD]
[TD]
8​
[/TD]
[TD]
-6.83​
[/TD]
[TD]
-27.33​
[/TD]
[TD][/TD]
[/TR]
</tbody>[/TABLE]


Thanks for the replies so far! On a second note, can you explain the table? We don't necessarily use slopes on the understanding that delta(velocity, position, or acceleration) will be the slope in question.
 
Upvote 0
The slope of the ramp determines the accelerating force on the car, no?

EDIT: Describe your experiment; what you do, what you record, and what result you're trying to calculate.
 
Last edited:
Upvote 0
The slope of the ramp determines the accelerating force on the car, no?

EDIT: Describe your experiment; what you do, what you record, and what result you're trying to calculate.

To your first question: Yes, although we can't just say "slope is 3 therefore A must be 3". We have to use kinematics to prove it. Why, I don't know but thus is life. After looking at the chart, I understand it. It took me a minute because of curriculum changes over the last year :D Thanks again!
 
Upvote 0

Forum statistics

Threads
1,224,416
Messages
6,178,509
Members
452,853
Latest member
philipnjk64

We've detected that you are using an adblocker.

We have a great community of people providing Excel help here, but the hosting costs are enormous. You can help keep this site running by allowing ads on MrExcel.com.
Allow Ads at MrExcel

Which adblocker are you using?

Disable AdBlock

Follow these easy steps to disable AdBlock

1)Click on the icon in the browser’s toolbar.
2)Click on the icon in the browser’s toolbar.
2)Click on the "Pause on this site" option.
Go back

Disable AdBlock Plus

Follow these easy steps to disable AdBlock Plus

1)Click on the icon in the browser’s toolbar.
2)Click on the toggle to disable it for "mrexcel.com".
Go back

Disable uBlock Origin

Follow these easy steps to disable uBlock Origin

1)Click on the icon in the browser’s toolbar.
2)Click on the "Power" button.
3)Click on the "Refresh" button.
Go back

Disable uBlock

Follow these easy steps to disable uBlock

1)Click on the icon in the browser’s toolbar.
2)Click on the "Power" button.
3)Click on the "Refresh" button.
Go back
Back
Top