Consider the collision between two hockey pucks in the figure below. They do not

Question

Consider the collision between two hockey pucks in the figure below. They do not stick together. Their speeds before the collision are v1i = 26 m/s and v2i =12 m/s. It is found that after the collision one of the pucks is moving along x with a speed of 4 m/s. What is the final velocity of the other puck?

magnitude?? in m/s

direction??? in degrees - counterclockwise from the +x axis

http://www.webassign.net/giocp1/7-p-024.gif

I know someone with V1=24, V2=12 and their speed along the xaxis is equal to 1. They got a corect answer of 19.805. How they did it is unfortunatly not giving me a corect answer.

they used 24cos(30)=20.78 then subtracted their speed 1m/s to give 19.78.

They then took (19.78^2 +1^2) and took the square root of this these numbers to give an answer of 19.805 which is correct for them but it doesnt work for me. Please Help!!!! I also need the direction the other person got the direction wrong trying the inverse tan(19.805)

Explanation / Answer

Along X-axis v2f*cos(theta) - v1f = v1i*cos(30) = 22.516

v2f*cos(theta) = 26.516

Along Y-axis v2f*sin(theta) - 0 = -v1i*sin(30) - 12 = -25

tan(theta) = 26.516/(-25) =

theta = -46.7 degrees

direction is 313.7 degrees

magnitude is v2f = 26.516/cos(-46.7) = 38.66 m/s

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