Presentation on theme: "Standards/Plan. Standards Standards Standards Processes."— Presentation transcript:
Simple Harmonic Motion (SHM) 1)
Warm Up 2) A block is pushed along a horizontal, frictionless surface, with a horizontal Force that varies as a function of time as shown in the graph here. The mass of the bloc is 3kg. If the block was at rest at time t=0, what is the speed of the block at time t=3?
Warm up 2
Warm Up 3) Three blocks of mass m, 2m, and 3m are placed adjacent to each other on a frictionless horizontal surface as shown above. A constant force of magnitude F is applied to the right. Which of the following statements is true?
4) Two masses, M>m, are connected by a light string hanging over a pulley of negligible mass. When the masses are released from rest, the magnitude of the acceleration of the masses is?
Warm Up 5) A mass of 2.0kg is attached to the end of a light cord to make a pendulum 5.0m in length. The mass is raised to an angle of 53 relative to the vertical, as shown, and released. The speed of the mass at the bottom of the swing is:
Warm Up 6) A cannon is mounted on a cart, and carrying a cannonball. The total mass of the cart, cannon, and ball is M, and the cart is rolling with no friction at a velocity v in the positive direction as shown above. The ball, of mass m, is fired with a velocity v ball in the positive x direction. What is the velocity of the cart and cannon after the ball is fired?
Warm Up 6)
Awesome Gas Video Awesome Gas Video Awesome Gas Video Awesome Gas Video NO WARM UP! NO WARM UP!
Warm Up 7) A student lies on a rigid platform of negligible mass, which is in turn placed upon two spring scales as shown above. The left scale at position 0 reads 200N, and the scale on the right at position L, reads 300N. Find the value of X in terms of L. a. X = 1/2 L b. X = 2/5 L c. X = 3/5 L d. X = 3/4 L e. X = 4/5 L PIVOT POINT
Warm Up 8)8)8)8)
9 ) A pendulum driven clock, located on earth, is set into motion by releasing its 10m long simple pendulum from a maximum angle of less than 10° relative to the vertical. At what approximate time t will the pendulum have fallen to a perfectly vertical orientation? (Use 10 for g)
10 ) By visual inspection, order the PV diagrams shown from the most negative work done on the system to the most positive work done on the system. A. a,b,c,d B. a,c,b,d C. d,b,c,a D. d,a,c,b
Announcements Pass Back Fluids Quiz: Thermo Quiz Friday!
What are important quantities in thermodynamics? Pressure Atoms colliding w/ wall of a container Pressure Atoms colliding w/ wall of a container Temperature How fast atoms move Temperature How fast atoms move Volume How much space atoms “need” to move freely Volume How much space atoms “need” to move freely Number of molecules Really big numbers Number of molecules Really big numbers
Kinetic Theory of Gases Assumptions for an IDEAL GAS 1)Atom are bouncy: Elastic collisions between atoms 2)Atoms are spread out: Far away unless colliding 3)Atoms are random: No preferred direction of motion (means pressure is equal everywhere in a container
Calculation – Units to use Pressure ALWAYS Pascals (N/m 2 ) Pressure ALWAYS Pascals (N/m 2 ) Temperature ALWAYS Kelvin (273 + o C) Temperature ALWAYS Kelvin (273 + o C) Volume ALWAYS m 3 (Liters/1000) Volume ALWAYS m 3 (Liters/1000) Number of molecules moles or molecules Number of molecules moles or molecules Moles = Molecules/6.02E23 R = 8.31J/molK R = 8.31J/molK K b = 1.38 E-23 J/K K b = 1.38 E-23 J/K
Equation’s so far 1. PV = nRT 2. PV = Nk b T 3. P 1 V 1 / T 1 = P 2 V 2 / T M is molar mass
Energy of a Gas 1. ΔU = Q + W 2. U = 3/2 nRT 3. U = 3/2 PV Energy Type (+)(-) U = Internal energy Temp INCREASETEMP DECREASE Q = HEATHEAD ADDEDHEAT REMOVED W = WorkGAS CONTRACTS (WORK ON) GAS EXPANDS (WORK BY)
Gas Process The thermodynamic state of a gas is defined by pressure, volume, and temperature. The thermodynamic state of a gas is defined by pressure, volume, and temperature. A “gas process” describes how gas gets from one state to another state. A “gas process” describes how gas gets from one state to another state.
T1T1 Isothermal Process (constant temperature) P V T = 0 (constant T) Hayon: Pull plunger up from halfway (slowly)
Isobaric Process (constant pressure) P V P = 0 (constant P) Isobaric Expansion Isobaric Contraction Hayon: Heat up the tank while allowing plunger to move
Isometric Process (constant volume) P V V = 0 (constant V) Hayon: Push to the top and then heat up or push to the bottom and then cool down NO WORK POSSIBLE!!
Adiabatic process (PERFECTLY insulated) P V T isotherm adiabat Q = 0 (no heat enters or leaves) NO HEAT IS TRANSFERED ΔU = W
Example Problem 0.25 moles of a gas are kept at 1150K. The gas undergoes adiabatic expansion, reaching a final temperature of 400K. How much work was done on or by the gas ? U = 3/2 nRT
Using PV Diagrams WORK = Area under a PV Diagram P V 100kpa 200kpa 300m 2 250m 2 Hayon: Test (remember area) and don’t use 1 way valve (+) = Contract (-) = Expand
Free Response Problems FR #1 as an Example FR #1 as an Example Web Assign: Thermo Assignment #2 Web Assign: Thermo Assignment #2 Then skip #2 and go to the back Then skip #2 and go to the back