Unit 2 Review. SPH4U Nov. 9, 2015

Transcription

1 Unit 2 Review SPH4U Nov. 9, 2015

2 Assessment Dates Quiz tomorrow ( Tuesday, Nov. 10) on Elastic and Inelastic Collisions Unit Test Thursday, Nov. 12

3 Next Unit Gravitational, Electric, and Magnetic Fields

4 Work The energy transferred to an object when a force acting on the object moves it through a distance Work is a scalar quantity

5 Equation and Units for Work Force x distance Work =

6 Positive Work Adds energy to an object For example the work: Increases the speed of the object Increases the height of the object

7 Negative Work Removes energy from the object For example the work: Decreases the speed of the object Decreases the height of the object

8 Zero Work Object experiences a force or a displacement or both, yet no work is done on the object. Example:

9 Energy Transformations & The Law of Conservation of Energy Total Mechanical Energy the sum of kinetic and potential energy When energy transforms from potential energy to kinetic energy the total mechanical energy remains constant

10 Law of Conservation of Energy

11 Power Rate of change in energy over time Rate of work done by a force over time

12 Elastic Potential Energy Associated with springs and other elastic objects A spring always tries to get to equilibrium

13 Spring Force

14 Spring Force

15 Hooke s Law The amount of force exerted by a spring is directly proportional to the displacement of the spring

16 Spring Constant (k): The constant of variation between the force exerted by an ideal spring and the springs displacement Corresponds to the stiffness of the spring Stiffer the spring the larger the k

17 Ideal Spring Any spring that obeys Hooke s Law, it doesn t experience any internal or external friction

18 Simple Harmonic Motion

19 Key Equations for SHM Combining Hooke s Law and Newton s 2 nd Law

20 Period of SHM

21 Hooke s Law: the (-) Conundrum Forces exerted by and applied to a spring A graph of the force exerted by the spring as a function of x has a negative slope A graph of the force applied to a spring as a function of x has a positive slope

22 Hooke s Law: Force exerted by a Spring A graph of the force exerted by a spring as a function of x has a negative slope F x = -kx If x > 0, then F x < 0 If the spring is stretched in the +x direction, it pulls in the opposite direction

23 Hooke s Law: Force exerted by a Spring The magnitude of the force exerted by a spring is written either as kx OR kx

24 Springs and Conservation of Energy For an isolated mass-spring system the total mechanical energy remains constant Total Mechanical Energy is made up of kinetic energy, gravitational potential energy, and elastic potential energy E E E E T K g e

25 More Conservation of Energy E Ti E Tf E E E E E E Ki gi ei Kf gf ef

26 Momentum The product of a moving object s mass and instantaneous velocity Vector quantitiy We will often have to consider components of momentum Equation:

27 Impulse: Change in Momentum Equal to the change in momentum of an object SI unit is the N s Vector Quantity Direction of impulse is the same as the direction of the change in momentum Formula:

28 Law of Conservation of Momentum When 2 or more objects collide, the total momentum just after the collision is equal to the to the total momentum just before the collision. Momentum is always conserved whether the colliding objects bounce off of one another or remain together

29 Law of Conservation of Momentum

30 Law of Conservation of Momentum

31 Interactions within a System Collisions the impact of one body with another Explosions a situation in which a single object or group of objects breaks apart Rocket Propulsion burning of fuel expels a continuous stream of gases at extremely high velocity

32 Momentum The product of a moving object s mass and instantaneous velocity Vector quantitiy We will often have to consider components of momentum Equation:

33 Impulse: Change in Momentum Equal to the change in momentum of an object SI unit is the N s Vector Quantity Direction of impulse is the same as the direction of the change in momentum Formula:

34 Perfectly Elastic Collisions Momentum and kinetic energy are conserved The colliding objects bounce off each other Solve using a linear-quadratic system of equations (2 equations 2 unknowns)

35 Perfectly Inelastic Collisions Only momentum is conserved Objects stick together perfectly so they have the same final velocity

36 Glancing Collisions in Two- Dimensions This is the good (fun) stuff!!!! The final velocity of each object involves 2 unknowns the 2 components of the velocity vector Consider the change in momentum for each component independently

37 Glancing Collisions in Two- Dimensions Express the conservation of momentum equation in terms or horizontal and vertical components

38 Review Questions Handouts given today ( I will post answers on the website ) Chapter 4 Self Quiz pg. 213 # 1 11 Chapter 4 Review Pgs # 1,2,4 11,21 24,50, 53-56, Chapter 5 Self Quiz Pg. 263 # 1-14

39 . More Review Questions Chapter 5 Review 6.4 Pgs # 1 4, 15,23,24,26 30,48,50,51 Unit 2 Self Quiz Pgs # 1 11, Unit 2 Review Pgs # 1 13, 63 74, 87,88,93

40 252 pg. 2 Pilsx R. 4 10*4=3 so o=tai' ELIDA = zt

41 Pg Gig Put PUI F Ymn vm%8mj ; I Vt. Required Vfz =?.5m1s[n3iE] Analysis : Assume elastic collision [ to. Ek is Conserved is conserved find Kd Steps Ey to determine direction '

42 0.32kg } = 0,18 kgmhgtflo.mg# kyng # 0.14 :# ;n =# # P. t 1%1=1.284) ftp.i#ix+pzi@l6kgx2omb)=(0.16kd(1.sn)cos , = ( ankh :) ( use ) 0, cg G 0.9 = Cose

43 - - Py - 0=(0.144%59)+(0.1*1.28) sine 0= ha -0,2 she sat 0,2176 CA H = she Toa tone tsinotkosot tone E = =