Find the direction of a blob of clay after impact?

[isukatphysics69]

Homework Statement

Homework Equations

impulse = mv

The Attempt at a Solution

so i found the velocity of the blob of clay now i am trying to find the direction.

i took the xcomponent initial stuff which was
0.04kg*4m/s*cos45 - 0.03kg*3m/s
Then set it to the final x component stuff which i thought would be = 0.09kg*xComponentSpeed*cosθ

I then divided by the 0.09kg*xComponentSpeed and took the inverse cosine of initialmomentum / 0.09kg*xComponentSpeed and got 0degrees

 

[isukatphysics69]

i see i made a mistake with the xComponentSpeed. if you replace xComponentSpeed with the speed of the actual blob of clay the answer will be partially correct with 0.80/1.00 points given

 

[isukatphysics69]

i need to now see how to get the other .20 points maybe a sign error

 

[isukatphysics69]

ok i just recomputed it and i am still getting partial credit

0.04kg*4m/s*cos45 - 0.03kg*3m/s
Then set it to the final x component stuff which i thought would be = 0.09kg*SPEED*cosθ

I then divided by the 0.09kg*SPEED and took the inverse cosine of initialmomentum / 0.09kg*SPEED
The result is a positive 72 degrees​

 

[isukatphysics69]

 

[isukatphysics69]

I think i see what my problem was but not sure, when i used the y component equations i got a -72.4 degrees and rounded to -70 and got full credit.
I think it had to be negative because that big blob of clay came flying down with a lot of momentum and smashed right into the smaller blobs of clay resulting in the whole new blob of clays momentum going in the southeast direction. i am unsure how to prove that it should be like that, all i know is that the y component equations gave me the correct sign. So was what i was doing the correct approach? i don't want to close the thread until i know 100% i am understanding everything. How should i have knows to use the y component stuff?

 

[ehild]

View attachment 224536

It is said "angles counter-clockwise from the horizontal are positive".