In a game of pool, the cue ball strikes another ball of the same mass and initia

Question

In a game of pool, the cue ball strikes another ball of the same mass and initially at rest. After the collision, the cue ball moves at 3.00 m/s along a line making an angle of -26° (i.e. below the x-axis) with the cue ball's original direction of motion (the x-axis), and the second ball has a speed of 1.971 m/s. Find the angle between the direction of motion of the second ball and the original direction of motion of the cue ball. Submit Answer Tries 0/10

Find the original speed of the cue ball. Submit Answer Tries 0/10

Is kinetic energy (of the centers of mass, don't consider the rotation) conserved? YES NO

Explanation / Answer

The other ball will move up making an angle a with x axid such that final y component of system is 0 since initial y component of momentum is 0
use:
m*1.971*sin a = m*3*sin 26
sin a= 0.667
a=41.9 degree
ANswer: Angle is 41.9 degree above x axis

Now use conservation opf momentum in x direction:
m*Vi = m*1.971*cos a + m*3*cos 26
Vi =1.971*cos 41.9 + 3*cos 26
Vi = 4.16 m/s
Answer: original speed was 4.16 m/s

initial kinetic energy = 0.5*m*(4.16)^2 = 8.67 J
Final kinetic energy = 0.5*m*(1.971)^2 + 0.5*m*(3)^2 = 6.44 J
So kinetic energy is not conserved

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