Pendulum question. come on! no one has gotten it right?

No one can possibly get this right, because tons of important information are missing.

1) we need information about hte pendulum to help determine the moment of inertia

2) we need to know where the ball hits the pendulum and in what direction

This is actually an angular momentum question.

If you treat it as a linear momentum problem (which is wrong because it does not account for the impact at the pendulum pivot), then this is what you'll get.

0.02*6 = 0.13002 * v

v = 0.923 m/s

KE = 5.53761e-2 J

*EDIT*

I corrected an earlier error. I thought the pendulum was 103 kg. Anyway, that impact at the pivot makes an enormous difference. By definition, a pendulum swings, thus is a rotating component. It's angular momentum that's important here, not linear momentum. In fact I'll go one step further to say that angular momentum about the pivot is conserved, but linear momentum is NOT conserved.

conservation of momentum m1v1=m2v2 103.0 g = 0.103 Kg

for an inelastic collision the m2 mass will be pendulum plus ball 0.103 +.02=0.123 Kg

so m1(ball)=.02 Kg v1 (ball) = 6 m/s so 0.12 Newton-seconds

then 0.12 n-s * 6 m/s = 0.72 joules kinetic energy of ball before collision

this will also equal kinetic energy of ball and pendulum after collision since conservation of momentum also applies to conservation of energy negating air friction and gravity.

velocity of ball and pendulum after will be v2=0.12/0.123 =0.9756 or

about 1 m/s

Not enough information.

if the speed of the ball is v

if the mass of the pendulum is m

speed after collision is V

momentum before collision is 103v

momentum after collision (103+m)V

103v = (103+m)V

V = 103v/(103+m)

KE = ½mV² = ½(103+m)(V)²

.

1) conservation of momentum

... You need to know the mass of the ball. Unless you want the answer in all variables.. Please provide this and the initial speed of the ball and I can help you further