Hey physics question

[Finns14]

So here is the question

A 46.0-kg skater is traveling due east at a speed of 2.10 m/s. A 62.0-kg skater is moving due south at a speed of 6.70 m/s. They collide and hold on to each other after the collision, managing to move off at an angle x south of east, with a speed of vf. Find (a) the angle and (b) the speed vf, assuming that friction can be ignored.

And here is the answer

a) 76.908715552297

b) 3.948927204077

I am rather confused any help would be very apprciated Thank!!!!

 

[notfred]

I like the omnidirectional skates they must be wearing.

 

[pray4mojo]

ill tell you that its an inelastic collision

 

[JasonE4]

Break it down into x and y components of the speed. X and Y components of moment are independently conserved.

X (east) direction:

m1v1 = (m1 + m2)v3

Y (south) direction:

m2v2 = (m1 + m2)v4

m1 = 46
m2 = 62
v1 = 2.1
v2 = 6.7

v3 = x component of final velocity
v4 = y component of final velocity

You should be able to figure it out from there..

 

[blahblah99]

Originally posted by: Finns14
So here is the question

A 46.0-kg skater is traveling due east at a speed of 2.10 m/s. A 62.0-kg skater is moving due south at a speed of 6.70 m/s. They collide and hold on to each other after the collision, managing to move off at an angle x south of east, with a speed of vf. Find (a) the angle and (b) the speed vf, assuming that friction can be ignored.

And here is the answer

a) 76.908715552297

b) 3.948927204077

I am rather confused any help would be very apprciated Thank!!!!

Use your momentum equations. You have two objects moving in a direction at a given magnitude (think vector). After they collide, it is one object with a new direction and new magnitude. What's the resulting vector?

 

[Finns14]

Thanks I will try to grind it out I am still a little confused

 

[dopcombo]

Each individual skater has a x and a y component in his movement.
Rationalise his velocity into those components.

Momentum is conserved in both dimensions, so
M(initial)V(Initial) = M(Final)V(Final)
This is true for both Vx and Vy.

Then once you have the new Vx and Vy, you can recombine that into the actual direction that the final mass is moving in.

And LOL at the inelastic collision. 🙂