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## natasha.aries 2 years ago A boulder is launched from the ground by a catapult with a vertical velocity of 13.0 m/s and a horizontal velocity of 15.0 m/s. It misses the enemy castle and hits the ground. How long did it take the boulder to hit enemy ground? (ignore air friction) A 0.38 s B 2.65 s C 0.75 s D 1.33 s

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1. cesckay

step by step.. find the initial speed of the boulder which is just the resultant component of both forces using Pythagoras theorem.

2. natasha.aries

wait so how would u do that?

3. cesckay

X= sqrt(13^2 + 15^2)

4. natasha.aries

and then?

5. cesckay

lol.. answer is B.. you dont have to find the resultant component since theres no angle.. sorry :( if you have the vertical component of the velocity, then just use********* time= 2v/g its kind of a long derivation though.. U r supposed to get 2.6503

6. cesckay

where v=13

7. natasha.aries

how do u know u dont use 15?

8. cesckay

it is not travelling horizontally right? so the components are independent of each other.. ig you were to plug in the value for the horizontal component, then the answer would be wrong.. the resultant velocity will give you a larger answer..

9. natasha.aries

oh okay that makes sense! thanks!

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