Projectile Motion Calculation: Finding the Landing Distance of a Launched Object

[physicsnobrain]

Homework Statement

A 500kg object is launched from the top of a 12m building with intial speed of 5.2m/s and angle of 38degrees. How far away does object land?

Homework Equations

y=vit + 1/2at^2
quadratic formula
d=vt

The Attempt at a Solution

first i separate the initial velocity into its x and y coordinates. Using cos and sin. Next I input this found value of the y direction velocity into the y=vit + 1/2at^2. I rearrange this formula and solve it as a quadratic for time, and I use the positive time value which I got as 1.92s. Next I multiply this time value by the velocity in the x direction I got from doing the cos of the initial velocity.

I end up getting the object lands 7.9 m away from the building. Can anyone check and see if this is right? Also the mass was negligble right?

 

[voko]

Your method is correct.

If you want your numbers to be checked, post the intermediate values you got (init. velocity components, time of flight).

 

[physicsnobrain]

Your method is correct.

If you want your numbers to be checked, post the intermediate values you got (init. velocity components, time of flight).

Well the initial velocity was 5.2m/s. The y component of this is 3.2m/s, and the x component is 4.097 m/s.

When I solve for time from the quadratic formula, I get -1.272s and 1.923s. I use the positive value cause you can't have negative time.

Now I just multiply the time by the x component velocity and get 7.9m.

 

[voko]

Everything looks good.

 

[physicsnobrain]

Everything looks good.

Thanks.