40A_Lab_6_InelasticCollisions6 - Physics 40A Inelastic...

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Physics 40A Electromagnetic Launcher (Blown-up view) Inelastic Collisions (Pre Lab Assignment Included) This week we will study some inelastic collisions on the air track. You will record the velocity of gliders before and after the collisions, and calculate the changes in momentum that occurred in each collision. Apparatus: The air track is provided with two gliders and two 50 gram weights. The gliders will have a “needle” and “wax” pair, one on each glider, so that they will stick together in a collision. Both gliders will have a metal armature that can be held by the electromagnet launcher. Each end of the air track is equipped with an electromagnet “launcher.” A power supply with switches is used to control the release of the gliders from the launchers. The mass of the gliders and the added weights will be measured with an analytical scale. You will add weights in pairs, one on each side of a glider, to make different masses for collisions. The motion of the gliders will be recorded by two photogate timers connected to the computer through the PASCO adapter. The Precision Timer software on the computer will record the time-of-passage of the gliders, and will compute the glider velocities for you. The Physics Only momentum is conserved in an “inelastic” collision. You will make collisions where only one glider is moving before the collision, and collisions where both gliders are moving. The general case of both movingis presented here. Note: you must be careful about the sign of the velocityof the gliders. A glider moving to the right has positive v, and one moving to the left has negative v. We begin with both gliders moving, one with mass m1moves with velocity v1i, and the other has mass m2and velocity v2i. Air Track Assembly (with Electromagnetic Launchers)
2 Colliding gliders before (above), and after (below). After the collision, the gliders (mass m1+ m2) have velocity vf. Conservation of Momentum gives Pi= Pf, or The change in total momentum in the collision should be zero. 0)()(221121=++==iififvmvmvmmPPPδProcedure - Perfectly Inelastic Collisions[5 points]A. Getting ready 1. Prepare and weigh the gliders and masses, and level the air track

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