What should be a simple kinematics question on MPrep...

[Kerosene Hat]

---

Members don't see this ad.

http://www.mcatquestion.com/findquestion.php?arg1=160

"Observe the following diagram which shows a ball resting at the top of a 10 m tall building. There is a target (named T) which is 3 m away from the building...If the ball begins to roll to the right and falls off the building with a rightward velocity of 10 m/s, about how long will the ball remain in the air before hitting the ground?"

Since there is no air resistance, I thought I could simply calculate the vertical component and safely ignore the horizontal component. Using x = vot + 0.5at^2, I got sqrt(2) as an answer, but this was not one of the answer choices.

The correct answer is 2.5 seconds, but the explanation seems roundabout. Why do we care about the final velocity at all?

Thanks!

 

[Cawolf]

I think you are mistaken - their answer is 2^(1/2) not 2.5.

I also just solved it using the vertical kinematics formula.

 

[popopopop]

Yeah, your answer is right. It's saying 10(2^.5) = 10(t), so t = 2^.5 = 1.4~

 

[Kerosene Hat]

Oops, I looked over it and just noticed that it is indeed 2^(1/2)! Thanks!