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# Ball thrown off a building time question

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1. Been given this question, and I'm sure it's to be solved with a quadratic equation but it's not really working out for me so far.

A ball's been thrown off a building and it's going at 60 km per hour, the building is 100 meters tall and the distance before it reaches the ground is;

d = ½gt^2 + vt

g = gravity and it's 10 ms^-2
t = time in seconds
v = initial velocity

I've to find the time for the ball when it's dropped ¼ the height of the building.

so I got;

5t^2 + 60t - 25 = 0

Am I on the right track?
2. (Original post by Brainfrozen)
Been given this question, and I'm sure it's to be solved with a quadratic equation but it's not really working out for me so far.

A ball's been thrown off a building and it's going at 60 km per hour, the building is 100 meters tall and the distance before it reaches the ground is;

d = ½gt^2 + vt

g = gravity and it's 10 ms^-2
t = time in seconds
v = initial velocity

I've to find the time for the ball when it's dropped ¼ the height of the building.

so I got;

5t^2 + 60t - 25 = 0

Am I on the right track?
You should probably covert from km/h to m/s before plugging that speed in since right now the equation doesn't make sense, otherwise you're on the right track.
3. (Original post by RDKGames)
You should probably covert from km/h to m/s before plugging that speed in since right now the equation doesn't make sense, otherwise you're on the right track.
It's sorted, thanks for your help!

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Updated: October 17, 2016
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