Please fill in all _____'s. Physlet Physics by Christian and Belloni: Exploration 8.4 (compadre.org) Open the simulation. This lab has different subscripts than the text. The text uses "A and B" for the two objects, this lab uses "1 and 2". The text uses "prime superscripts" for final, such as vA', while the lab spells out "initial and final" as subscripts, such as v1final. We will inelastic first, then elastic collisions Inelastic collisions set up: click the " Check, then click..." box just below the simulation. Set the v2 to 1 m/s. Click run. They stick together. Before the collision, v1 = +2 m/s. You will see high KE bars on the right. Then the collision occurs, and you see the velocities converge to common final value, during the time "t" that is the time used in the impulse equation. KE bars drop during this time. Once converged, the two carts proceed to the right (and then stop). We have both masses at 1 kg. Let's begin the 3 step procedure in the lecture, to solve for v2. Note the subscripts, p1i is "mass 1 initial momentum", and p1f is "mass 1 final momentum". Question 1. Step 1. Total pinitial = m1 v1i + m2 v2i = _____ kg m/s. Here p1i = m1 v1i, p2i = m2 v2i, and pinitial = p1i + p2i. Step 2. Total pfinal = ____ v2f. (combined mass, m1 + m2 stuck together, is the coefficient of v2f the final speed). Step 3. Solve, v2f = _______ m/s. Does this check with the simulation's v2? Yes/No. Question 2. Impulse function, must be done for one object. In an inelastic collision, this calculation only uses the mass of one object, even when coupled to the other object after the collision. First m1 calculation of Impulse1, then m2 for Impulse2: m1: momentum before = p1i = _____ kg m/s. momentum before, use m1 mass and initial speed. momentum after = p1f = _____ kg m/s. momentum after, use m1 mass alone, and its final speed. Impulse1 = p1f - p1i = _______ kg m/s. Impulse1 is for m1. m2: momentum before = p2i = _____ kg m/s. Use m2 mass and speed. momentum after = p2f = _____ kg m/s. Use m2 mass alone, and final speed. Impulse2 = p2f - p2i = _______ kg m/s. Impulse2 is for m2. The impulses are equal and opposite, if not redo above blanks. The time along the horizontal axis is actually in msec (not seconds). We need to estimate the contact time, by looking at the curves in velocity. Use where they start to curve, to when they stop. These two points are at about 250 to 400 msec. We need the "time width" of this "contact time". The contact time "t" is the same for both masses, so no subscript is used. Estimate, t = ____ sec (less than or equal to .15 s). Then calculate the forces for each mass, from F1 t = Impulse1, F1 = ______ N, and from F2 t = Impulse2, F2 = _______ N. Are F1 and F2 equal and opposite? Yes/No. Question 3. Calculate three KE's, KE1 = _____ J, KE2 = _____ J, KEfinal = _____ J (cart 1 and cart 2 initially, then both together). Total energy lost, subtract final total from initial total of KE1+KE2, then KElost = _______ J (positive number). Elastic Collision. Set up, click on the Check... box at bottom, to turn it off. Reset v2 = 0 m/s, m1 = .5 kg. (m2 = 1 kg, v1 = 2 m/s) Click run. You will see them recoil from one another. We first need to get final velocities, using the equation from the lecture. Neither is stationary, before or after. We will use equation subscripts here. Calculate: Question 4. v1f = ______ m/s (nearest hundredth, calculation). V2f = ______ m/s (nearest hundredth, calculation). Question 5. Step 1. Total pinitial = m1 v1i + m2 v2i = _____ kg m/s. Step 2. Total pfinal = m1 v1f + m2 v2f = _____ kg m/s. Step 3. Skip, as we know the final velocities. Question 6. Now the impulses and KE's for both carts. m1 impulse: Impulse1 = p1f - p1i = _______ kg m/s. m2 impulse: Impulse2 = p2f - p2i = _______ kg m/s. The impulses are equal and opposite, if not redo above blanks. We need to estimate the contact time, by looking at the curves in velocity. Use where they start to curve, to when they stop. These two points are at about 350 to 425 msec. We need the "time width" of this "contact time". Estimate, t = _____ sec (less than or equal to .075 s). Then calculate the forces for each mass, from F1 t = Impulse1, F1 = ______ N, and from F2 t = Impulse2, F2 = ______ N. Are F1 and F2 equal and opposite, and do they point towards final speeds of each mass? Yes/No. Question 7. Calculate three KE's, KE1 = ____ J, KE2 = ____ J, KEfinal = _______ J (cart 1 and cart 2 initial, then total for both final). Total energy lost, subtract final total from initial total of KE1+KE2, KElost = _____ J Question 8. Inelastic and elastic collision summary: Is momentum conserved in inelastic and elastic collisions? Yes/No. Which type of collision has KE conserved? Inelastic/Elastic.