Lab 18: Impulse and Momentum 2. DETERMINE THE MASS OF THE CART ESSENTIAL QUESTION Impulse Mass of Cart Distance Average Force Average Time What factors most influence the speed of the ball in sports like tennis, baseball, raquetball, or soccer, where a ball is struck with a bat, raquet, hand or foot? Relate your response to the -2 ug 50 cm 7:8 N 1.5 sec concepts of force, time, momentum and impulse. Weigh the cart with the spring scale, then convert (F,) in Newtons to (m) in kilogram LEARNING TARGETS using g = 10 N/kg. Add "1 kg" to the mass since in step 3 you'll be putting the 1-kg mass on the cart. I can define the terms "Momentum" and "Impulse". an state the Momentum-Impulse Theorem. 3. MEASURE THE TIME THAT THE RUBBER BAND APPLIES A FORCE TO THE CART can cite the Momentum-Impulse Theorem in describing collisions. I can show the connection between Newton's 2nd Law and the Momentum-Impulse Theorem. Set up the photogates so that one starts the timer when you release the cart at 50 cm, and the other stops the timer when the back of the cart reaches the rest position of the MATERIALS AND PROCEDURE rubber band. Low-friction cart Flag for timers Rubber Bands Place the 1-kg mass on the cart, resting against the back of cart so that the mass doesn't Two lab stools Photogate Timers Meter Stick Spring Scale 1-kg mass slide when the cart accelerates forward. The photogate timers should be set on PULSE, so that the first gate starts the timer and the second gate stops it. Release the cart from the 50 cm mark and let it roll completely free of the rubber band. Stop it before it hits anything. Gather at least three consistent times, average the result and enter the average into your data table. ANALYSIS 1. GRAPH THE "STRETCH" OF YOUR RUBBER BAND Plot Force on the dependent axis and Distance on the independent axis Plot your data and sketch the line suggested by the data. Comment on the relationship between Force and Distance for a rubber band, and the term "elastic". Explain how Hooke's Law describes elastic materials. Calculate the slope of the graph. . Explain what property of the rubber band is described by the slope of the graph. 1. FIND THE FORCE THAT WILL BE APPLIED TO THE CART BY THE RUBBER BAND Explain why the graph suggests that you can find an "average force" which was applied to the cart. Average Force Compute the average force applied to the cart using Hooke's Law, Fave = 1/2F, and Fave= Distance Force 0 cm 10 cm 20 cm 30 cm 40 cm 50 cm EF/6. Discuss the three values. 1. EN 2. 7 1 / 3. 4 N C. UN |7. 5 N 2. CALCULATE THE CHANGE IN THE CARTS MOMENTUM Assemble the equipment as shown above. The stools are to be 3 feet apart. . Calculate the average velocity of the cart while the rubber band was pulling it. Use the spring scale to measure the force needed to pull the cart against the rubber band Determine V1, V2, and the change in velocity for the cart. from a rest position to the starting position of 50 cm back from rest. Record the force Calculate the change in the carts momentum using Ap = m.Av. each 10 cm (10 cm, 20 cm, 30 cm, etc.).3. CALCULATE THE IMPULSE THAT THE RUBBER BAND "GAVE" TO THE CART . Calculate the Impulse given to the cart by the rubber band using Ap = Fave't. . . Comment on the units "N-s" and "kg.m/s". Compare the calculated Impulse with the change in momentum from Step 2, including an explanation for why they're not a "perfect" match. Calculate the cart's average acceleration using a = Av/t. . Calculate the Net Force acting on the cart using Newton's 2nd Law (EF = ma). . Calculate the Impulse given to the cart by the rubber band using Ap = EF.t Comment on how closely these two impulse results compare with the change in momentum you calculated. Calculate your percent error and accuracy using EF.t and m.Av. State the "Impulse Theorem-Change in Momentum". SYNTHESIS QUESTIONS 1. Define the two terms: "impulse" and "momentum". 2. Show how Newton's 2nd Law of Motion results in the Impulse-Change in Momentum equation (ZF .t = m.Av)