Velocity/Acceleration/displacement Help

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The discussion focuses on understanding how to calculate displacement during a car's braking period, given its initial and final speeds and uniform acceleration. A specific example is provided where a car traveling at 15 m/s decelerates to 10 m/s with an acceleration of -2.0 m/s². Participants clarify that acceleration is essential for determining the time taken to reach the final speed, which is necessary for calculating distance. The appropriate formulas for displacement, considering known velocities and acceleration, are emphasized as crucial for solving the problem. The conversation concludes with a better understanding of how to approach the calculations involved in this scenario.
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Homework Statement



I need help with acceleration/displacment, mainly how far something moves during a acceleratopn period

Homework Equations



Alright, right now i am learning about velocity and acceletarion and i have a question/problem i need help with.

I know the formula for acceleration and stuff, but how do you find out how far the an object. in this case a car moved during the breaking period?

This is the exact question:
A driver of a car traveling at 15 m/s applies the breaks, causing a uniform acceleration of -2.0 m/s^2. how long does it take the car to accelerate to a final speed of 10.0 m/s? How far has the car moved druing the breaking period?



The Attempt at a Solution


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austin1250 said:

Homework Statement



I need help with acceleration/displacment, mainly how far something moves during a acceleratopn period

Homework Equations



Alright, right now i am learning about velocity and acceletarion and i have a question/problem i need help with.

I know the formula for acceleration and stuff, but how do you find out how far the an object. in this case a car moved during the breaking period?

This is the exact question:
A driver of a car traveling at 15 m/s applies the breaks, causing a uniform acceleration of -2.0 m/s^2. how long does it take the car to accelerate to a final speed of 10.0 m/s? How far has the car moved druing the breaking period?

The Attempt at a Solution

-

Here are some equations that might help:
https://www.physicsforums.com/showthread.php?t=110015

You know a and V and want to find t. And then you want to find X.
 
LowlyPion said:
Here are some equations that might help:
https://www.physicsforums.com/showthread.php?t=110015

You know a and V and want to find t. And then you want to find X.

Ah I see. then does accelaration even matter?
Can't you just do Change in velocity Times change in time?
 
austin1250 said:
Ah I see. then does accelaration even matter?
Can't you just do Change in velocity Times change in time?

Of course acceleration matters. When you don't have the time as in this problem you need the acceleration to determine the unknown time. Now for this question they also ask what the distance is and that can be found from a formula for known velocities and acceleration.
 
yeah that's what i meant, i got the first part i needed help with how far/distance it traveld after it accelerated. but yeah i get it now thanks
 
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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