
#1
Jan2409, 03:49 PM

P: 24

[b]1. The problem statement, all variables and given/known data
An airplane is flying with a velocity of 85.0 m/s at an angle of 19.0 degrees above the horizontal. When the plane is a distance 106 m directly above a dog that is standing on level ground, a suitcase drops out of the luggage compartment. [b]2. Relevant equations How far from the dog will the suitcase land? You can ignore air resistance. [b]3. The attempt at a solution I attempted to use YYinitial = Voy(t)  1/2(g)(t^2) I solved for t and i got t = 4.651 s. That answer was incorrect. I then tried using Vx = (85m/s)(cos19) = 80.37 Vy = (85m/s)(sin19) = 27.67 I then tried adding them using V = sqrt{(80.1^2)  (27.7^2)} = 75.16 m/s I then did R = Vox(t) but the answer I got wasn't correct. Help! 



#2
Jan2409, 03:58 PM

HW Helper
P: 5,346

Welcome to PF.
The problem is that the vertical velocity continues to carry it upward before it goes down. What if you reduced the problem to throwing a ball straight up at 27 m/s and you are standing on a 105m cliff? Find that time and multiply by the horizontal velocity. 



#3
Jan2409, 04:11 PM

P: 24

I'm still not sure how to solve this =(




#4
Jan2409, 04:16 PM

HW Helper
P: 5,346

An airplane flying with a velocity...You got the wrong answer from the quadratic. 



#5
Jan2409, 04:23 PM

P: 24

Ohh! I didn't realize my mistake. I used 0 for Voy instead of 85m/s which is the initial velocity.
I solved the quadratic using the positive value and I got 1.168s. I then multiplied that by 85m/s to find the range and I got 99.28m. Does that sound correct? 



#6
Jan2409, 04:45 PM

HW Helper
P: 5,346

Your initial vertical velocity is your Voy Besides your quadratic should yield t to hit the ground. It can't get to the ground in 1 sec from 100 m. 



#7
Jan2409, 04:47 PM

P: 24

I'm sorry, I'm confused again.




#8
Jan2409, 04:51 PM

HW Helper
P: 5,346





#9
Jan2409, 05:01 PM

P: 24

85 (+ or ) sqrt{(85^2)  4(4.9)(106) all divided by 2(4.9)
I think that when I added the 85 to the problem I ended up with 1.168 Now when I subtracted the 85 to the problem I got 18.51s. Which seems more realistic. 



#10
Jan2409, 05:18 PM

HW Helper
P: 5,346

Your vertical component of velocity is 85*Sin19° = 27.67 That should yield 0 = 105 + 27.67*t 4.9*t^{2} That quadratic yields 8.246 s I use this online calculator btw: http://www.math.com/students/calcula.../quadratic.htm 



#11
Jan2409, 05:20 PM

P: 24

Ohhh I understand now. Thank you so much for your help!




#12
Jan2409, 05:23 PM

P: 24

How far from the dog will the suitcase land?
I'm still having issues finding the distance. 



#13
Jan2409, 05:30 PM

HW Helper
P: 5,346

You have time to hit the ground. You have the horizontal velocity projected along the ground ... Speed * time = distance. 


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