The conservation of momentum in 2D

AI Thread Summary
The discussion centers on a physics problem involving the conservation of momentum during a collision between two hockey pucks of equal mass. One puck is initially moving at 5.4 m/s, while the other is at rest. After the collision, the pucks move at angles of 33 degrees and 46 degrees relative to the original puck's direction. The user breaks down the momentum into x and y components but struggles to proceed due to the complexity of the variables involved. Suggestions include using trigonometry and the Pythagorean theorem to resolve the momentum vectors after the collision.
Dakkers
Messages
17
Reaction score
0

Homework Statement


Two hockey pucks of equal mass undergo a collision on a hockey rink. One puck is initially at rest, while the other is moving with a speed of 5.4m/s. After the collision, the velocities of the pucks make angles of 33 degrees and 46 degrees relative to the original velocity of the moving puck. Determine the speed of each puck after the collision.

(Assuming the moving puck is object A and the stationary puck is object B)
Ma = Mb
Va1 = 5.4m/s
Vb1 = 0m/s
Deflection Angle of A = 33
Deflection Angle of B = 46

Homework Equations


p(before) = p(after)


The Attempt at a Solution


Okay, the first thing I did was broke it into components as it's in two dimensions. For x,

p(before) = p(after)
(Ma)(Va1x) + (Mb)(Vb1x) = (Ma)(Va2x) + (Mb)(Vb2x)
(5.4) + 0 = Va2x + Vb2x
5.4 = Va2x + Vb2x

for y,

p(before) = p(after)
(Ma)(Va1y) + (Mb)(Vb1y) = (Ma)(Va2y) + (Mb)(Vb2y)
0 + 0 = Va2y + Vb2y
Va2y = -Vb2y

And then I don't know where to go from there. I've thought about trig and using Pythagorean theorem but there's too many variables.
 
Physics news on Phys.org
Set up a drawing of the resultant momentum vectors after the collision. Trig and pythagorean theorem might be necessary here but draw a picture first and see what you can deduce from it.
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top