Equations for Accelerated Motion 4

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Homework Help Overview

The problem involves a motorcycle that decelerates from an initial speed of 30 m/s to a stop over a distance of 150 m, with the goal of determining its acceleration. The subject area pertains to kinematics, specifically equations of motion under uniform acceleration.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants discuss the application of the kinematic equation v^2 = vinitial + 2aΔx and share their attempts at solving for acceleration. There is a focus on the calculations and the interpretation of negative acceleration as deceleration. Some participants express confusion about the results and question the validity of their calculations.

Discussion Status

The discussion is ongoing, with participants providing feedback on each other's calculations and clarifying misunderstandings. Some guidance has been offered regarding the interpretation of negative acceleration and the relationship between acceleration, time, and distance. There is an acknowledgment of mistakes in the initial posts, but no consensus has been reached on the final interpretation of the results.

Contextual Notes

Participants note potential typos and misunderstandings in the original equations and calculations. There is also a light-hearted acknowledgment of errors due to distractions, such as lack of coffee, which may affect clarity in problem-solving.

Medgirl314
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Homework Statement


A motorcycle traveling at 30 m/s comes to a stop over a distance of 150 m. What was the motorcycle's acceleration?


Homework Equations


v^2=vinitial+2aΔx


The Attempt at a Solution


I tried plugging in what I know.

0=900+2a*150 m

Then I divided 150 m and 900 by 150:

0=6+2a

This yields an answer of -4. It doesn't seem right, but I can't place why. I think I may have needed to divide the v^2 by 150, but that's 0/150, which wouldn't make sense. Thanks in advance for a reply!
 
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Medgirl314 said:

Homework Statement


A motorcycle traveling at 30 m/s comes to a stop over a distance of 150 m. What was the motorcycle's acceleration?

Homework Equations


v^2=vinitial+2aΔx

The Attempt at a Solution


I tried plugging in what I know.

0=900+2a*150 m

Then I divided 150 m and 900 by 150:

0=6+2a

This yields an answer of -4. It doesn't seem right, but I can't place why. I think I may have needed to divide the v^2 by 150, but that's 0/150, which wouldn't make sense. Thanks in advance for a reply!
does it?...check your final equation, you have done the rest of it correctly...it should be -ve because of deceleration (retardation), it just shows acceleration acts in direction opposite to its initial velocity

##0=6+2a##
##a=-3##

Edit: I think it was a typo, but this is what the equation is v^2=(vinitial)^2+2aΔx...your calculations are correct except the very end of it.!
 
Last edited:
Oh! Okay. I made a mistake in the post, I actually thought it was -2 m/s . I see what you did there, I added in my head instead of dividing. The main reason I thought it was wrong didn't have a reason. It just seemed like it should be different because I couldn't place how an acceleration of -2 or -3 would be enough to slow the car, but now that I look again, it makes sense. Thank you for a polite and helpful reply!
 
The car?? I meant the motorcycle. Sorry. Blame it on lack of coffee syndrome.
 
Medgirl314 said:
Oh! Okay. I made a mistake in the post, I actually thought it was -2 m/s . I see what you did there, I added in my head instead of dividing. The main reason I thought it was wrong didn't have a reason. It just seemed like it should be different because I couldn't place how an acceleration of -2 or -3 would be enough to slow the car, but now that I look again, it makes sense. Thank you for a polite and helpful reply!

no problem!...just to make it seem reasonable you can use ##v=v_{0}+a.t##, solving for time gives ##10~seconds##. It doesn't stop immediately, it slowly decelerates therefore time is comparatively large and so is the distance. I hope this makes more sense now!
 
Medgirl314 said:
The car?? I meant the motorcycle. Sorry. Blame it on lack of coffee syndrome.

I got that, no problem.
 
It does! Thanks, you have given some of the nicest replies I have found on here. If you have a moment, maybe you would go to my other Equations for Accelerated Motion problems and check those?

Thanks again!
 
NihalSh said:
I got that, no problem.

HA! :smile:
 

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