4A Chapter 1 Introduction to Basic Mechanics 2019 (1).pptx

Power Engineering 4A Unit #1 Chapter #1 Introduction to Basic Mechanics Fun Math In a year you could be making some good money and are people ready to manage it? Do you know your needs vs wants? Mortgage/rent $1200/month Groceries...

Power Engineering 4A Unit #1 Chapter #1 Introduction to Basic Mechanics Fun Math In a year you could be making some good money and are people ready to manage it? Do you know your needs vs wants? Mortgage/rent $1200/month Groceries $400/month Car loan $300/month Car insurance $150/month Car gas $200/month Utilities/NG/water/lights $250/month Cable/internet $120/month Entertainment/eat out $200/month Cell phone $100/month Life insurance/health/dental $200/month $3120 not counting travel, emergencies, presents etc. This equates to $37,440 Net Ontario overall tax rate along with federal tax is around 42% and remember you need to count in EI and CPP which comes off your check each pay until its paid You will require $70,000 gross to make the above. Or $33.65/hour There will be OT available in most cases and paid at 1 1/2 times or maybe double time REMEMBER you have NOT paid your self yet!!! Compound interest is a WONDERFUL thing! CPP is going to be severely depleted and maybe non existent by the time 20 year olds get to claim it unless the government makes changes. If you invest $300/month at 3% for 40 years then you’ll have $275,000 If you invested $600/month at 3% for 40 years then you’ll have $550,000 You’ll need more like a pension besides CPP and EI Food for thought Learning Outcome When you complete this chapter you should be able to: – Apply basic terms and calculations used in the study of mechanics Learning Objectives Here is what you should be able to do when you complete each objective: – Define mass, force, acceleration, velocity and weight – Perform simple calculations involving force, pressure, work, power and energy Introduction to Basic Mechanics Mechanics is a branch of physics that deals with forces and their effects of these forces on bodies at rest or in motion. Used in the study of forces acting upon: – Boiler supports or girders – Leverage when lifting or tightening something – Work done like pumping water into a tank – Work done in raising an elevator in its shaft. Each of the above processes involves the action or movement of forces. Introduction to Basic Mechanics There are two branches of mechanics: Static Dynamic Static deals with forces and their effect on rigid bodies at rest. Dynamic deals with motion and the effects of forces acting upon rigid bodies in motion. Newton’s Laws of Motion Every body will continue in it’s state of rest or uniform motion in a straight line, unless acted upon by another force acts upon it. The rate of change of motion is proportional to the force producing the change and takes place in the direction in which the force acts. For every action there is an equal and opposite reaction. When one object exerts a force on a second object, the second object exerts a reactive force of equal magnitude in the opposite direction of the first object. https://ca.video.search.yahoo.com/yhs/search?fr=yhs-rotz-001&hsi mp=yhs-001&hspart=rotz&p=video+newton+3+laws#id=1&vid=703 9cf5f96c4749ead768f17f02b7732&action=click Objective #1 Define mass, force, acceleration, velocity and weight Mass & Force Mass – The quantity of matter a body contains ( SI system is the kilogram Kg ) – Weight is NOT the same as mass! Weight requires a gravitational force or attraction Force – Any action on a body which tends to change it’s size, shape or its state of rest or motion ( SI system is Newton N ) Mass & Weight ( force) https://ca.video.search.yahoo.com/yhs/search;_ylt=AwrEzeKnbWxdaXgA5DA87olQ;_ylu=X3oDMTBncGdyMzQ0BHNlYwNzZWFyY2gEdnRpZAM-;_ylc=X1MDM TM1MTIxNjcwMARfcgMyBGFjdG4DY2xrBGNzcmNwdmlkA21WSXhjVEV3TGpGSGlSYTRXdXpHd2dEQ09UY3VNUUFBQUFDOExRZm4EZnIDeWhzLXJvdHot MDAxBGZyMgNzYS1ncARncHJpZANlWVNaaXhodFNZS0g3b2xnc0s4ZUdBBG5fcnNsdAM2MARuX3N1Z2cDMARvcmlnaW4DY2EudmlkZW8uc2VhcmNoLnlha G9vLmNvbQRwb3MDMARwcXN0cgMEcHFzdHJsAwRxc3RybAMyMgRxdWVyeQNtYXNzJTIwdmVyc3VzJTIwd2VpZ2h0BHRfc3RtcAMxNTY3Mzg3MDYw?p=m ass+versus+weight&ei=UTF-8&fr2=p%3As%2Cv%3Av%2Cm%3Asa&fr=yhs-rotz-001&hsimp=yhs-001&hspart=rotz#id=1&vid=653023fab2d4207cab285253497 c0946&action=view Acceleration and Velocity To understand acceleration it is useful to understand what velocity is Velocity is: The rate of change of position (displacement) that occurs during a given time in meters per second or m/s V = change in position time Meters/second ( m/s ) in SI system https://www.youtube.com/watch?v=O22zcaELpaA Acceleration and Velocity https://ca.video.search.yahoo.com/yhs/search;_ylt=AwrGHTa0bWxdZ40AGDI87olQ;_ylu=X3oDMTBncGdyMzQ0BHNlY wNzZWFyY2gEdnRpZAM-;_ylc=X1MDMTM1MTIxNjcwMARfcgMyBGFjdG4DY2xrBGNzcmNwdmlkA1VjYVdqREV3TGp GSGlSYTRXdXpHd2dEcU9UY3VNUUFBQUFDODlzd1AEZnIDeWhzLXJvdHotMDAxBGZyMgNzYS1ncARncHJpZANpV nU2VTFMdVF0Mjh3QUo5cVhPZHFBBG5fcnNsdAM2MARuX3N1Z2cDMARvcmlnaW4DY2EudmlkZW8uc2VhcmNoLnlh aG9vLmNvbQRwb3MDMARwcXN0cgMEcHFzdHJsAwRxc3RybAMyNQRxdWVyeQNzcGVlZCUyMHZlcnN1cyUyMHZlb G9jaXR5BHRfc3RtcAMxNTY3Mzg3MzUx?p=speed+versus+velocity&ei=UTF-8&fr2=p%3As%2Cv%3Av%2Cm%3Asa&f r=yhs-rotz-001&hsimp=yhs-001&hspart=rotz#id=18&vid=e6e0b49b0234cadfdf51bc2faf4dcf1c&action=view Acceleration and Velocity Acceleration and Velocity 0 10m 60m 90m Carol walks 10 m North in 8 seconds, Then travels another 50 meters in 49 seconds She then travels south 30 meters in 18 sec and continues 19 meters north in 20 seconds. What is her velocity? V = change in position time V = 10 + 50 - 30 + 19 8 + 49 + 18 + 20 V= 0.521 m/sec North Acceleration and Velocity Acceleration is the rate of change of velocity that occurs over a given time The units for acceleration are meters per second squared or m/s2 Acceleration https://www.bing.com/videos/search?q=What+is+acceleration&&view=d etail&mid=B4AE93A16F509032705DB4AE93A16F509032705D&FORM =VRDGAR Acceleration https://ca.video.search.yahoo.com/yhs/search;_ylt=AwrEzeGGb2xdYmoA6Ao87olQ;_ylu=X3oDMTBncGdyMzQ0BHNlY wNzZWFyY2gEdnRpZAM-;_ylc=X1MDMTM1MTIxNjcwMARfcgMyBGFjdG4DY2xrBGNzcmNwdmlkA29RQzJXekV3TGp GSGlSYTRXdXpHd2dBdE9UY3VNUUFBQUFEWXdpcE0EZnIDeWhzLXJvdHotMDAxBGZyMgNzYS1ncARncHJpZAN5 SzJKd1ZfclFwZUQ5OWhjYnZHRGRBBG5fcnNsdAM2MARuX3N1Z2cDMQRvcmlnaW4DY2EudmlkZW8uc2VhcmNoLnl haG9vLmNvbQRwb3MDMARwcXN0cgMEcHFzdHJsAwRxc3RybAMzMwRxdWVyeQNhY2NlbGVyYXRpb24lMjB2ZXJlc 3VzJTIwdmVsb2NpdHkEdF9zdG1wAzE1NjczODc2NTE-?p=acceleration+veresus+velocity&ei=UTF-8&fr2=p%3As%2Cv %3Av%2Cm%3Asa&fr=yhs-rotz-001&hsimp=yhs-001&hspart=rotz#action=view&id=13&vid=fcdd9c190545f3274e23855 c83c7c861 Acceleration Acceleration – Is the rate of change of velocity in m/s2 Acceleration = Change in Velocity time Or Acceleration = Vf – Vi t Where Vf = Final velocity Vi = Initial velocity t = time Acceleration & Velocity Solution Acceleration = Change in Velocity ————————— time = 20 m/s / 4 seconds = 20/4 x m/s/s = 5 m/s2 Acceleration 20 seconds later V =100 m/s V= 40 m/s How fast does the cat accelerate? A = (Vf –Vi) t A = (100m/s – 40 m/s) 20 sec A = 3m/s2 Mass Force & Acceleration A dragster starts from rest and attains a speed of 50 m/s in 10 seconds. What is the acceleration? Solution Where Vf is 50 m/s and Vi is 0 m/s (rest) and time is 10 seconds A = Vf - Vi / time A = 50 m/s - 0 m/s / 10 seconds A = 50 m/s / 10 seconds A = 5 m/s2 Mass Force & Acceleration The faster a velocity changes, the larger the acceleration will be Therefore – Average Acceleration = change in velocity (or speed) Elapsed Time Or A= V t Mass Force & Acceleration A plane accelerates at 8.5 m/s2 for 4.5 seconds. Find it’s velocity? V=At = 8.5 m/s2 x 4.5 sec = 38 m/s Mass Force & Acceleration A driver decelerates at a rate of 3.00 m/s2 for 5 seconds. Find the drivers new speed if the car was originally travelling 20 m/s Known A = -3.00 m/s2 T = 5.00 sec Vi = 20 m/s V=At Where V = Vf- Vi Substitution V = At Vf – Vi = At Then Vf = Vi + ( At) Vf = 20m/s + (- 3.00 m/s2 x 5 sec) Vf = 5.00 m/s Velocity and Acceleration A velocity of 5 m/s means that an objects position will change by 5 m in one second Acceleration of 5 m/sec2 means that the objects velocity will change by 5 m/s in 1 second. It is a rate of change Mass Force and Acceleration Force = Mass x Acceleration = Kg x m/s2 = Newton What does this mean? – If a force of 1N is applied to a mass of 1 kg then that mass will accelerate at 1m/s2 Or – If a mass of 1kg is found to be accelerating at 1m/s2 then a force on 1 N must be acting upon it Therefore 1 N = 1kg m/sec 2 – If an unknown mass is found to be accelerating at 1m/s2 under the influence of 1 N then that mass must be 1 Kg. Mass Force and Acceleration Free falling objects undergo constant acceleration. In the absence of gravity objects of different mass will fall at the same rate. This was proven in 1971 when astronaut David Scott dropped a feather and hammer on the moon! Mass Force and Acceleration A ball of 14 kg is dropped from the a building. What will be the force acting upon it as it falls? F=MxA = 14 x 9.81 m/s 2 = 137.34 N Acceleration due to Gravity – The earth’s gravitational effects cause a body falling to earth at a velocity of 9.81 m/s during the elapse of each second – Therefore – Acceleration due to gravity = Change in velocity time = 9.81 m/s 1 sec = 9.81 m/s2 Remember this!! Force due to Gravity Force of gravity can be said to be on a 1 kg mass falling to earth - F = Mass x Acceleration - F = 1kg x 9.81 m/s2 - F = 9.81 kg m/s2 - or - F = 9.81 Newtons (N) - Remember this!! Mass Force and Acceleration Objective #2 Perform simple calculations involving force, pressure, work, power and energy Pressure and Force Pressure – Is the force per unit area that acts in a direction to or at right angles to the surface Therefore Pressure = Force Area If 1 Newton is acting on 1 square meter, it exerts a pressure of 1 Pascal or Pa The Pascal is a very small unit so usually we use kiloPascals when dealing with higher pressures Pressure and Force A force of 2000 N is exerted uniformly over 0.25 square meters. What is the pressure? Pressure = Force Area = 2000 0.25 = 8000 Pa = 8 kPa Pressure and Force A pressure of 22 kPa is being exerted on a 0.55 m2 area what is the force acting upon it? Pressure = Force Area Force = 22,000 x 0.55 = 12,100 N Power, Work & Energy https://ca.video.search.yahoo.com/yhs/search;_ylt=AwrGHTY0AW1dXaUAZSs87olQ;_ylu=X3oDMTBncGdyMzQ0BH NlYwNzZWFyY2gEdnRpZAM-;_ylc=X1MDMTM1MTIxNjcwMARfcgMyBGFjdG4DY2xrBGNzcmNwdmlkAzgwMmJYek V3TGpGSGlSYTRXdXpHd2dCN09UY3VNUUFBQUFDSG52ZnkEZnIDeWhzLXJvdHotMDAxBGZyMgNzYS1ncARnc HJpZAN6WUgwWVY4Q1RjQ2IyeGQ5M3VMRDZBBG5fcnNsdAM2MARuX3N1Z2cDMQRvcmlnaW4DY2EudmlkZW8 uc2VhcmNoLnlhaG9vLmNvbQRwb3MDMARwcXN0cgMEcHFzdHJsAwRxc3RybAMyMwRxdWVyeQN3b3JrJTIwZm9 yY2UlMjBkaXN0YW5jZQR0X3N0bXADMTU2NzQyNDg0Nw--?p=work+force+distance&ei=UTF-8&fr2=p%3As%2Cv %3Av%2Cm%3Asa&fr=yhs-rotz-001&hsimp=yhs-001&hspart=rotz#id=18&vid=bd1cfca686c37254769307210a61911 f&action=view Work Work If a force is applied to a body and causes it to move through a distance then work is done. Work is the product of the force (N) applied and the distance (m) moved – Work Done = Force x Distance If a force of 1 Newton moves an object 1 meter the work done is 1 Joule (J) 1 Nm = 1 J Work A force of 4000 N is acting on a body and causes it to move 30 meters. What is the work done by this force? Work = F x d = 4000N x 30m =120,000 J = 120 kJ Power Power is the rate of doing work or the quantity of work done in a given time Power = work done = Joule time sec Joule / second = Watt Again the Watt is a small unit so generally kiloWatt is used or kW Power A force of 200 N is moved a distance of 10 M in 20 seconds, what power is developed? Power = F x d time = 200 x 10 20 = 100 Watts Energy Defined as the capacity of a body or substance to perform work or a body possesses energy when its capable of doing work. Energy can be contained in many forms and its presence is ONLY observed by its effects The study of mechanics is mainly concerned with 2 forms of energy which are Potential Energy and Kinetic Energy Potential Energy Is the ability of a body to do work by virtue of its position PE = m x g x h PE = joules (J) Potential Energy Ability of a body to do work by virtue of its position For example a body of water held back by a dam contains potential energy due to its position and can be made to do work Potential Energy mass x gravitational force x vertical height kg x m/s/s x m OR N x m ( Nm ) PE = m x g x h PE = Joules (J) Potential Energy What is the potential energy of a 200 kg piano that is to be dropped from a 30m height? PE = m x g x h = 200 kg x 9.81 m/s/s x 30 m = 58,860 J = 58.9 kJ Potential Energy What potential energy would an object have if a force of 300 N was exerted on it at a height of 50 m? PE = m x g x h Since F = m x a PE = F x h = 300 x 50 = 15000 J = 15 kJ Energy Is the ability of a body to do work due to it’s motion KE = 1/2m x velocity Kinetic Energy A 500 kg mass is moving at a velocity of 200 m/sec. What is it’s kinetic energy? KE = 1/2 mass x Velocity (squared) = ½ x 500 kg x (200 m/s)2 = 10,000,000 J = 10,000 KJ = 10 MJ Knowledge Exercises Chapter #1 Knowledge Exercises Chapter #1