Physics Homework #2

[Jess]

The drawing shows three particles far away from any other objects and located on a straight line. The masses of these particles are mA = 363 kg, mB = 517 kg, and mC = 154 kg. Find the magnitude and direction of the net gravitational force acting on each of the three particles (let the direction to the right be positive).

http://www.webassign.net/CJ/p4-98.gif


particle A: 0.0000567 N
particle B: 0.0000349 N
particle C: ?

I got the first two correct but for some reason the third one was wrong (I put in 0.0000916). I don't understand why. The force on C is the combination of A on C and B on C so F_AC + F_BC.

F_AC = 6.63E(-6) and F_BC is 8.50E(-5). I added them and got 9.16E(-5), so how is that wrong? The values of F_AB, F_BC, and F_AC are correct as I've used them to calculate the first two particles


EDIT: bleh, it was negative. Never mind






Stuck on another one
A 1501-kg submarine rises straight up toward the surface. Seawater exerts both an upward buoyant force of 17,263 N on the submarine and a downward resistive force of 1087 N. What is the submarine's acceleration?

10.78 is the wrong answer

I practiced another version:
A 1571-kg submarine rises straight up toward the surface. Seawater exerts both an upward buoyant force of 15,492 N on the submarine and a downward resistive force of 1037 N. What is the submarine's acceleration?

The answer was -0.599...no idea how they got THAT.


a = ΣF/m but I got 10.78 from (17263 - 1087)/1501, which is wrong.

so can anyone help me figure out what I'm doing wrong? -_-

[TheBigUnit]

Stuck on another one
A 1501-kg submarine rises straight up toward the surface. Seawater exerts both an upward buoyant force of 17,263 N on the submarine and a downward resistive force of 1087 N. What is the submarine's acceleration?

10.78 is the wrong answer

I practiced another version:
A 1571-kg submarine rises straight up toward the surface. Seawater exerts both an upward buoyant force of 15,492 N on the submarine and a downward resistive force of 1037 N. What is the submarine's acceleration?

The answer was -0.599...no idea how they got THAT.


a = ΣF/m but I got 10.78 from (17263 - 1087)/1501, which is wrong.

id tell you if i didnt forget ap physics over the summer haha, in all honesty though i believe these questions might be too complex for the average VTer

[teen.jpg]

Oh yay, this is what I'm going to have to do in Honors Physics? I'll just go sleep on a highway now

[TheBigUnit]

Oh yay, this is what I'm going to have to do in Honors Physics? I'll just go sleep on a highway now

kind of but not really

[Jess]

id tell you if i didnt forget ap physics over the summer haha, in all honesty though i believe these questions might be too complex for the average VTer

I didn't think they are that complex for the average VTer...as long as you took physics in high school...and didn't forget (like me -_-) ...I took Honors in the last year of high school and forgot everything

Oh yay, this is what I'm going to have to do in Honors Physics? I'll just go sleep on a highway now

Sort of. I'm taking an introduction to physics 1 in college and it goes at a much faster pace than high school physics, obviously

[teen.jpg]

I didn't think they are that complex for the average VTer...as long as you took physics in high school...and didn't forget (like me -_-) ...I took Honors in the last year of high school and forgot everything



Sort of. I'm taking an introduction to physics 1 in college and it goes at a much faster pace than high school physics, obviously

Well that makes me feel a lot better ... I mean at least for now.

[Jess]

I solved it! I needed to factor in gravity

should be (17263-1087-(9.8*1501))/1501

= 0.977

[Harley Quinn]

OP request lock. :locked2: