Impulse. calculate the impulse given to an object calculate the change in momentum as the result of an impulse

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1 Add Important Impule Page: 386 Note/Cue Here NGSS Standard: N/A Impule MA Curriculum Framework (2006): 2.5 AP Phyic 1 Learning Objective: 3.D.2.1, 3.D.2.2, 3.D.2.3, 3.D.2.4, 4.B.2.1, 4.B.2.2 Knowledge/Undertanding Goal: Skill: what impule i calculate the impule given to an object calculate the change in momentum a the reult o an impule Language Objective: Undertand and correctly ue the term impule. Accurately decribe and apply the concept decribed in thi ection uing appropriate academic language. Set up and olve word problem involving impule. Note: impule ( J ): a orce applied to an object over an interval o time. Impule i a vector quantity. An impule caue a change in momentum, and the amount o the impule i equal to the change in momentum. The impule alo equal orce time time: J F t p p p Impule i meaured in the ame unit a momentum (newton-econd): 1N 1 kgm i Ue thi pace or ummary and/or additional note. AP Phyic 1: Algebra-Baed

2 Add Important Impule Page: 387 Note/Cue Here I the orce i changing with time, the area under a orce-time graph i the impule or change in momentum: In the above graph, the impule rom time zero to t 1 would be Δp 1. The impule rom t 1 to t 2 would be Δp 2, and the total impule would be Δp 1 + Δp 2 (keeping in mind that Δp 2 i negative). Sample Problem Q: A baeball ha a ma o kg and i pitched with a velocity o 38 m toward home plate. Ater the ball i hit, it velocity i 52 m toward the outield ence. I the impact between the ball and bat take place over an interval o 3.0 m, ind the impule given to the ball by the bat, and the orce applied to the ball by the bat. A: The ball tart out moving toward home plate. The bat applie an impule in the oppoite direction. A with any vector quantity, oppoite direction mean we will have oppoite ign. I we chooe the initial direction o the ball (toward home plate) a the poitive direction, then the initial velocity i 38 m, and the inal velocity i - 52 m. Becaue ma i calar and alway poitive, thi mean the initial momentum i poitive and the inal momentum i negative. Furthermore, becaue the inal velocity i about 1½ time a much a the initial velocity (in the oppoite direction) and the ma doen t change, thi mean the impule need to be enough to negate the ball initial momentum plu enough in addition to give the ball about 1½ time a much momentum in the oppoite direction. Ue thi pace or ummary and/or additional note. AP Phyic 1: Algebra-Baed

3 Add Important Impule Page: 388 Note/Cue Here In the momentum bar chart, notice that we are adding an impule in the negative direction, and the inal momentum end up in the negative direction. By convention, we deine the poitive direction a into the ytem and the negative direction a out o the ytem. Thi mean that in thi problem, we draw the momentum low diagram to how momentum lowing out o the ytem (i.e., in the negative direction). Now, olving the problem numerically: J p p pi J m v mvi m( v vi ) J (0.145)(52 ( 38 )) N The colliion take place over a time interval o 3.0 m = J F t F(0.0030) F 4350 N Ue thi pace or ummary and/or additional note. AP Phyic 1: Algebra-Baed

4 Add Important Impule Page: 389 Note/Cue Here Homework Problem 1. A tudent i ruhing to cla and collide with a vice principal, who wa tanding till jut beore the colliion. The vice principal ha a ma o 100. kg, and the tudent ha a ma o 50. kg, and had a velocity o 2.0 m beore the colliion. a. What i the velocity o the entangled vice principal and tudent ater they collide? Anwer: 0.67 m b. I the colliion lated or 0.020, calculate the impule and the orce applied to the vice principal. Anwer: impule: 67N orce: N Ue thi pace or ummary and/or additional note. AP Phyic 1: Algebra-Baed

5 Add Important Impule Page: 390 Note/Cue Here 2. An 800 kg car travelling at 10 m come to a top in 0.50 in an accident. a. What wa the impule applied to the car? Anwer: N b. What wa the average net orce on the car a it came to a top? Anwer: N 3. A 0.80 kg ball wa dropped rom a height o 2.0 m above the ground. It rebounded to a height o 1.6 m. The contact between the ball and the ground lated or a. What wa the impule applied to the ball? Anwer: 9.59 N b. What wa the average net orce on the ball? Anwer: 213N upward Ue thi pace or ummary and/or additional note. AP Phyic 1: Algebra-Baed

6 Add Important Impule Page: 391 Note/Cue Here 4. A ball with ma m wa dropped rom a height h o above the ground. It rebounded to a height o h. The contact between the ball and the ground lated or time Δt. (You may ue your work rom problem #3 above to guide your algebra.) a. What wa the impule applied to the ball? Anwer: J p m 2 g ho h b. What wa the average net orce on the ball? m 2g ho h F t Ue thi pace or ummary and/or additional note. Anwer: AP Phyic 1: Algebra-Baed