Object Velocity Question help!

[bad at math guy]

Hi was wondering if i could get some help with this question

-An object is allowed to free fall from rest from a height of 9 m. What will be its velocity on striking the ground?

---My solution to this was to simply multiply the 9m by 9.81m/s... which is wrong the solution posted to this question is 13.29m/s

Any help would be greatly appreciated thank you

 

[wjm11]

Hi was wondering if i could get some help with this question

-An object is allowed to free fall from rest from a height of 9 m. What will be its velocity on striking the ground?

---My solution to this was to simply multiply the 9m by 9.81m/s... which is wrong the solution posted to this question is 13.29m/s

Any help would be greatly appreciated thank you

I'll give you some hints:

1) One thing that must be true in your work is that the units must work out right. You multiplied "m" times "m/s^2" (distance times acceleration, or meters times meters per second squared). That would result in "m^2/s^2", which is not velocity. Velocity should be "m/s", right? So, you need an equation that will multiply and/or add things that end up in m/s. Understanding this will help you avoid the mistake of simply multiplying random variables together.

2) Just Google "kinematics equations":

2a) https://www.google.com/search?q=kin...B-nkyQGLqYDYBg&ved=0CEMQsAQ&biw=1583&bih=1040

2b) http://www.physicsclassroom.com/class/1dkin/u1l6a.cfm

3) In choosing from the available equations (after reading the instructional material), it's important to ask ourselves, "What pieces of information am I given in the problem"? Those variables must appear in the equation we use. So look for equations that have both distance and velocity in them (as opposed to time, which is not given in this problem).

Hope that helps.

 

[bad at math guy]

thank you

 

[Dale10101]

Well there you go ....

... you are no longer "bad at math guy" you are now "getting better at math guy".