Lab_3_Linear_Momentum

Experiment 3 - Elastic Collision (2-dimentional collision) Collect the information (masses, angles, and velocities) before collision Parameter Ball 1 Ball 2 Mass of ball kg 0.5 0.5 Angle before collision 25.4 0 x velocity before collision 0.61 0.3 y velocity before collision 0.29 0 x momentum before collision kg.m/s 0.31 0.15 y momentum before collision kg.m/s 0.14 0 Angle after collision degree 41.9 -6.58 x velocity after collision m/s 0.39 0.52 y velocity after collision 0.35 -0.06 x momentum after collision kg.m/s 0.2 0.26 y momentum after collision kg.m/s 0.17 -0.03 (1) P xi = 0.31 + 0.15 = 0.46 kg . m / s., P xf = 0.2 + 0.26 = 0.46 kg . m / s. P yi = 0.14 + 0 = 0.14 kg . m / s, P yf = 0.17 - 0.03 = 0.14 kg . m / s. Hence, P xi = P xf , and, P yi = P yf , i.e., momentum is conserved, (2) KE i = 0.5 x ( 0.61^ 2 + 0.29^ 2 ) / 2 + 0.5^ 2 x ( 0.3^ 2 + 0^ 2 ) / 2 = 0.137 J, KE f = 0.5 x ( 0.39^ 2 + 0.35^ 2 ) / 2 + 0.5^ 2 x ( 0.52^ 2 + 0.06^ 2 ) / 2 = 0.137 J. We have , KE i = KE f means that the kinetic energy is conserved. Experiment 4 Parameter Ball 1 Ball 2 Mass of ball kg 0.5 0.5 Velocity before collision m/s 0.5 0 Momentum before collision kg.m/s 0.25 0 Velocity after collision m/s 0.25 0.25 Momentum after collision kg.m/s 0.125 0.125 (1) Total momentum before collision = 0.5 + 0 = 0.5 kg . m / s.,Total momentum after collision = 0.125 + 0.125 = 0.5 kg . m / s, (2) Total kinetic energy before collision = 0.5 x 0.5^ 2 / 2 + 0.5 x 0^ 2 / 2 = 0.125 J, 3

Experiment 5 - Let’s play billiards (Optional) Set both balls at the same mass. Give ball 1 some velocity and ball 2 at rest. (1) Head on collision (before/left and after/right collision) (2) (2) Collision with angle (before/left and after/right collision) Use the momentum and energy consevation as discussed in class (the dot product term must be zero) to explain the results. momentum conservation ⃗ v 1 i = ⃗ v 1 f + ⃗ v 2 f => v 1 i 2 = v 1 f 2 + v 2 f 2 + 2 ⃗ v 1 f ⃗ v 2 f energy conservation v 1 i 2 = v 1 f 2 + v 2 f 2 => v 1 i 2 = v 1 f 2 + v 2 f 2 Question Use your best knowledge to discuss why conservation of momentum is effective for both elastic and inelastic collisions, while conservation of energy is only good for elastic cases. Where the energy goes for inelastic collision? Momentum is effective and conserved for both elastic and inelastic collisions ,because the total momentum of both objects before and after the collision is the same. However, the kinetic energy is not conserved. Some of the kinetic energy is converted into sound, heat, and deformation of the objects. 6