Physics 101: Lecture 11 Momentum And Impulse
Exam IIPhysics 101: Lecture 11Momentum and Impulse Today’s lecture will cover Textbook Sections 7.1-7.5Physics 101: Lecture 9, Pg 1
Comments: Exam tonight – 7 PM (5:15 PM conflict) Free points for lecture and checkpoint!Physics 101: Lecture 9, Pg 2
Momentum and Impulse Momentum p mv» Momentum is a VECTOR Impulse I FDt» Impulse is just the change in momentum: I DpPhysics 101: Lecture 9, Pg 3
Key Ideas Earlier: Work-Energy FNet m amultiply both sides by d FNet d m a d (note a d ½ Dv2) FNet d ½ m Dv2 WNet DKEDefine Work and Kinetic Energy This Time: Impulse-Momentum FNet m a FNet m Dv/Dt (note a Dv/Dt ) FNet D (mv)/Dt Dp/Dt INet DpDefine Impulse and MomentumdemoPhysics 101: Lecture 9, Pg 4
Checkpoint 1A magician yanks a tablecloth out from under somedishes. Miraculously, the dishes remain on the tablewhere they were. Briefly explain why the dishes werenot given much impulse by the tablecloth.Impulse is force multiplied by time, so the dishes were not givenmuch impulse since the time was so small.Uh.magic. DUH. Good thing we know that physics is allgibberish and the real answer to these questions is magic.The cloth must be silky smooth.the magician is not as 'magical' as he seems-- like the membersof his audience, he is a slave to the laws of physics Physics 101: Lecture 9, Pg 5
ACT (w/ demo)Two identical balls are dropped from the same height onto thefloor. In each case they have velocity v downward just beforehitting the floor. In case 1 the ball bounces back up, and incase 2 the ball sticks to the floor without bouncing. In whichcase is the magnitude of the impulse given to the ball by thefloor the biggest?A. Case 1correctB. Case 2Bouncing BallSticky BallC. The same I Dp I Dp Vi -5 m/sVf 5 m/s mvfinal – m vinitial mvfinal – m vinitial m( vfinal-vinitial) m( 0-vinitial) 2mv mvPhysics 101: Lecture 9, Pg 6
ACTIn both cases of the above question, thedirection of the impulse given to the ball by thefloor is the same. What is this direction?A. UpwardcorrectB. DownwardtimePhysics 101: Lecture 9, Pg 7
ACTsYou drop an egg onto 1) the floor 2) a thickpiece of foam rubber. In both cases, the eggdoes not bounce (demo).In which case is the impulse greater?A) FloorB) FoamI DPSame change in momentumC) the sameIn which case is the average force greaterA) FloorB) FoamC) the sameDp F DtF Dp/DtSmaller Dt large FPhysics 101: Lecture 9, Pg 8
Pushing Off Fred (75 kg) and Jane (50 kg) are at rest on skates facing each other.Jane then pushes Fred w/ a constant force F 45 N for a time Dt 3seconds. Who will be moving fastest at the end of the push?A) FredB) SameC) JaneFredJaneF 45 N (positive direct.)F -45 N Newton’s 3rd lawI 45 (3) N-s 135 N-sI -45 (3) N-s -135 N-sI DpI Dp mvf – mvi mvf – mviI/m vf – vi vfI/m vf - vi vfvf 135 N-s / 75 kgvf -135 N-s / 50 kg 1.8 m/sNote: Pfred Pjane -2.7 m/s (1.8) 75 (-2.7) 50 0!Physics 101: Lecture 9, Pg 9
Momentum is Conserved LikeEnergy, Momentum is “Conserved”,meaning it can not be created nor destroyed Can be transferred TotalMomentum does not change with time.This is a BIG deal!Physics 101: Lecture 9, Pg 10
Impulse and MomentumSummaryFNetDt Dp For single object . FNet 0 momentum conserved (Dp 0) For collection of objects FNet 0 total momentum conserved (DPtot 0) FNet mtotal aPhysics 101: Lecture 9, Pg 11
Momentum ACTA car w/ mass 1200 kg is driving north at 40 m/s, and turnseast driving 30 m/s. What is the magnitude of the car’s changein momentum?A) 0 B) 12,000C) 36,000D) 48,000E) 60,000Pinitial m vinitial (1200 Kg) * 40 m/s 48,000 kg m/s NorthPfinal m vfinal (1200 Kg) * 30 m/s 36,000 kg m/s EastNorth-South:Pfinal – Pinitial (0 – 48000) -48,000 kg m/s30 m/sEast-West:Pfinal – Pinitial (36000 - 0) 36,000 kg m/s40 m/sMagnitude :Sqrt(P2North P2East ) 60,000 kg m/sPhysics 101: Lecture 9, Pg 12
Checkpoint 2 & 3Is it possible for a system of two objects to have zero totalmomentum while having a non-zero total kinetic energy?1. YES2. NOcorrect“an explosion! BOOM.”“two identical cars, sayPorsche's, runningtowards each other atidentical speeds and if you are BruceWillis, it may take outa helicopter.”“If Superman and Bizarro were flying dirrectly at each other in thevacuum of space, they would both have scalar kinectic energy, andequal and opposite momentum.”demoPhysics 101: Lecture 9, Pg 13
ACTMovies often show someone firing a gun loaded withblanks. In a blank cartridge the lead bullet is removedand the end of the shell casing is crimped shut toprevent the gunpowder from spilling out. When a gunfires a blank, is the recoil greater than, the same as, orless than when the gun fires a standard bullet?A. greater thanB. same asC. less thancorrectpgun -pbulletIf there is no bullet then pbullet 0 so pgun 0As if ice skater had no one to push Physics 101: Lecture 9, Pg 14
Summary Impulse I FDt» Gives change in momentum I Dp Momentum p mv» Momentum is VECTOR» Momentum is conserved (when FNet 0) S mvinitial S mvfinalPhysics 101: Lecture 9, Pg 15
Physics 101: Lecture 9, Pg 3 Momentum and Impulse Momentum p mv »Momentum is a VECTOR Impulse I FDt » Impulse is just the
Introduction of Chemical Reaction Engineering Introduction about Chemical Engineering 0:31:15 0:31:09. Lecture 14 Lecture 15 Lecture 16 Lecture 17 Lecture 18 Lecture 19 Lecture 20 Lecture 21 Lecture 22 Lecture 23 Lecture 24 Lecture 25 Lecture 26 Lecture 27 Lecture 28 Lecture
CHAPTER 3 MOMENTUM AND IMPULSE prepared by Yew Sze Ling@Fiona, KML 2 3.1 Momentum and Impulse Momentum The linear momentum (or "momentum" for short) of an object is defined as the product of its mass and its velocity. p mv & & SI unit of momentum: kgms-1 or Ns Momentum is vector quantity that has the same direction as the velocity.
Physics 101 Lecture 13 Angular Momentum Asist. Prof. Dr. Ali ÖVGÜN EMU Physics Department www.aovgun.com. February 16, 2020 Angular Momentum Torque using vectors Angular Momentum. February 16, 2020 The torque is the cross product of a force vector with the position vector to its point
Momentum: Unit 1 Notes Level 1: Introduction to Momentum The Definition Momentum is a word we sometime use in everyday language. When we say someone has a lot of momentum, it means they are on a roll, difficult to stop, really moving forward. In physics, momentum means "mass in motion". The more mass an object has, the more momentum it has.
Momentum ANSWER KEY AP Review 1/29/2018 Momentum-1 Bertrand Momentum How hard it is to stop a moving object. Related to both mass and velocity. For one particle p mv For a system of multiple particles P p i m i v Units: N s or kg m/s Momentum is a vector! Problem: Momentum (1998) 43. The magnitude of the momentum of the
momentum is kg·m/s. Linear Momentum Linear momentum is defined as the product of a system's mass multiplied by its velocity: p mv. (8.2) Example 8.1Calculating Momentum: A Football Player and a Football (a) Calculate the momentum of a 110-kg football player running at 8.00 m/s. (b) Compare the player's momentum with the
1. Impulse and Momentum: You should understand impulse and linear momentum so you can: a. Relate mass, velocity, and linear momentum for a moving body, and calculate the total linear momentum of a system of bodies. Just use the good old momentum equation. b. Relate impulse to the change in linear momentum and the average force acting on a body.
Choir Director: Ms. Cristy Doria Organist: Dr. Devon Howard Choir Accompanists: Madison Tifft & Monte Wilkins After the benediction, please be seated as the graduates leave the sanctuary. The classes of 2018 & 2019 are hosting an invitation-only dinner in the Fellowship Hall in honor of the graduates and their families. Special Thanks to
