Calculating Velocity of a Free-Falling Object

[bad at math gu]

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... which formula should be used for this question?

Any help would be greatly appreciated thank you

 

[collinsmark]

Hello bad at math gu,

Welcome to Physics Forums!

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... which formula should be used for this question?

Any help would be greatly appreciated thank you

That would be sort of the right approach if you were to allow an object to fall from rest for 9 seconds, but not 9 meters. (and you forgot to square the seconds in your acceleration units: 9.81 m/s²)

Find one of your kinematics equations for uniform acceleration that has initial and final velocity, acceleration and displacement (but not time). That's the easiest way to solve this problem.

You can find such an equation here: https://www.physicsforums.com/showthread.php?t=110015

 

[bad at math gu]

HA got it thank you