L10EX10.2-HockeyPucks-audio

L10EX10.2-HockeyPucks-audio - Which one? Again, note the...

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Two hockey pucks of the same mass collide as shown. Find the velocities after impact and the amount of energy lost if e = 0.75 Definitely an impact problem – what are the different principles you would apply? Probably some conservation of momentum, might use the e equation. First you have to define your n and t directions (see page 223-224). What happens in the t-direction? What about the n-direction? What happens here? No other outside forces or impulses, so can apply conservation of linear momentum. Write out the equation. Masses are equal, so cancel out. Make sure you set up proper coordinates and + direction, so you can see B has a negative velocity. Need one other equation.
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Unformatted text preview: Which one? Again, note the negative velocity of B. We usually leave the after impact velocities as positive and just see how the math turns out. Combine the two components to get a final velocity and direction. Find beginning and end kinetic energies, then find percentage lost. Reflection: Note that the energy lost isnt just the e squared for this more complex impact. It also seems reasonable that A bounces back in the x direction, and B bounces in the + x direction. Given: Find: v A = 6 m/s, v B = 10 m/s, e= 0.75 v A and energy lost Problem type: Note we have made the assumption that no force acts in the y direction Note that 10 cos 30 = 8.66 t n...
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