Calculating Projectile Motion: Solving for Distance and Height

[physics_geek]

Homework Statement

A ball is tossed from an upper-story window of a building. The ball is given an initial velocity of 8.20 m/s at an angle of 15.0° below the horizontal. It strikes the ground 3.00 s later.
(a) How far horizontally from the base of the building does the ball strike the ground?
4.90wrong check mark m
(b) Find the height from which the ball was thrown.
wrong check mark m
(c) How long does it take the ball to reach a point 10.0 m below the level of launching?

Homework Equations

i think the equations are r= v^2(sin2theta)/g
h= v^2(sintheta)2/2g

The Attempt at a Solution

i tried pluggin in the values to get how far it traveled and the height..but I am getting it wrong

any help would be appreciated

 

[mgb_phys]

Work out the velocity component downward.
Then it's just the normal moving object equations except the initial velocity isn't zero.

 

[physics_geek]

im not sure wat you mean by that

make the velocity -8.2?
im so confused

 

[cristo]

You need to resolve the velocity vector into horizontal and vertical components. Then, what mgb is saying, is you consider the vertical component.

 

[physics_geek]

o ok into two different components

so they give me 8.2 m/s
thats my resultant vector rite?

so i just do 8.2(cos15) ??

 

[mgb_phys]

Draw a diagram (triangle) - it should be obvious how much of the diagonal speed goes horizontally and how much vertically.

 

[physics_geek]

alrite cool
thanks a lot guys