How do I calculate acceleration from displacement and velocity?

[ocigano]

I am new to Physics and I need help on this problem


A skater increases her speed uniformly from 2.0 meters per second to 7.0 meters per second over a distance of 12 meters. The magnitude of her acceleration as she travels this 12 meters is?

A. 2.4 m/s squared
B. 3.8 m/s squared
C. 1.9 m/s squared
D. 2.2 m/s squared

Can you please give me an explanation of how to solve this since this seems pretty easy?

thanks

 

[hage567]

You must show some work in order to get help. Do you know your kinematic equations? You only need one equation to solve this. Can you explain what is confusing you?

 

[ocigano]

My teacher taught me a=v/t and I get the answer A but it says that I am wrong. But I don't have the T so I don't know what to do from then on.

 

[hage567]

I'm sure there are derivations of some other useful kinematic equations in your textbook (if you were given one). But what you can do is start with the definition of average acceleration

a_{ave} = \frac{\Delta v}{\Delta t}

The displacement (distance) of the car will be the average velocity of the car multplied by the time interval \Delta t

So that is \Delta x = (\frac{v_o + v}{2}) \Delta t

So arrange this for \Delta t and substituting it into your first equation will allow you to solve for a in terms of displacement.

Does that make sense?

See https://www.physicsforums.com/showpost.php?p=905663&postcount=2

This site might help: http://hyperphysics.phy-astr.gsu.edu/hbase/mot.html#mot1