# Help w/ projecetile motion w/ angled launch problem

## Homework Statement

A bowling ball rolls off an angled roof. The roof is sloped downward at 18.4 degrees and it is 12m above the ground. The question is how long does it take the ball to hit the ground?

## Homework Equations

Δx=viΔt+1/2a(Δt)^2
I know this is the equation I have to use but I'm having trouble isolating t.

## The Attempt at a Solution

I used quad formula and ended up getting Δt=1.56s but I don't think that's right. The working equation I got was Δt=(-2ghi)^(1/2)/g .I assumed Vi was 0. I don't know how to do this, help please!

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PeterO
Homework Helper

## Homework Statement

A bowling ball rolls off an angled roof. The roof is sloped downward at 18.4 degrees and it is 12m above the ground. The question is how long does it take the ball to hit the ground?

## Homework Equations

Δx=viΔt+1/2a(Δt)^2
I know this is the equation I have to use but I'm having trouble isolating t.

## The Attempt at a Solution

I used quad formula and ended up getting Δt=1.56s but I don't think that's right. The working equation I got was Δt=(-2ghi)^(1/2)/g .I assumed Vi was. I don't know how to do this, help please!
How far down the roof did the ball roll before launching of the edge? In other words; at what speed did the ball leave the roof?

EDIT: and is the time you are after, the time taken after it leaves the roof, or the time taken after it was released at the ridge of the roof and began rolling?

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I think it might be missing some information.

the angle is there for some reason.

That's all the info to this problem and I would assume it's asking for how the ball takes to hit the ground after it's left the roof.

PeterO
Homework Helper
That's all the info to this problem and I would assume it's asking for how the ball takes to hit the ground after it's left the roof.

If that is all the information that is provided then the answer is: "this problem is incalculable due to insufficient information"

Have you entered the question in the exact words in which the original question was stated?

It looks more like your interpretation of the question.

Well, here's the exact question. A bowling ball rolls off an angled roof. The roof is sloped downward at 18.4°, and the eaves are 12.0 meters above the ground. a.)How long does it take the ball it hit the ground?

PeterO
Homework Helper
Well, here's the exact question. A bowling ball rolls off an angled roof. The roof is sloped downward at 18.4°, and the eaves are 12.0 meters above the ground. a.)How long does it take the ball it hit the ground?
What is part b, c, etc