SPH 3U Completed Energy Lessons S1 2024 PDF

LESSON TOPIC: WORK DONE BY A FORCE LEARNING GOALS We will understand what happens when a force does work on an object We will be able to determine when the work done is positive, when it is negative, and when it is zero We will be able to calculate the amount of work done by individual forces, a...

LESSON TOPIC: WORK DONE BY A FORCE LEARNING GOALS We will understand what happens when a force does work on an object We will be able to determine when the work done is positive, when it is negative, and when it is zero We will be able to calculate the amount of work done by individual forces, and the total work done on an object HW: Pg. 229 # 1 – 5,7,9 LESSON TOPIC: WORK DONE BY A FORCE When a force acts on an object, and the object moves a distance, the force can do work on the object. In the example to the left, a shovel is used to exert force to move the snow horizontally. The component of the force that acts down does no work on the snow, only the component of the force that acts left does work on the snow. When a force does work on an object, it transfers energy to the object which is equal to the amount of work done. The angle between the This change in energy can show up in any form (kinetic, potential) force vector and displacement vector Since work equals change in energy, it is measured in Joules (J) (never greater than 180 degrees) 1  LESSON TOPIC: WORK DONE BY A FORCE What sign does work have under the following conditions on the angle theta? 1) 2) 3) 4) LESSON TOPIC: WORK DONE BY A FORCE Work done can be zero under 3 conditions: Case #1: Zero displacement Case #2: Zero force Case #3: Force and Displacement are perpendicular 2  LESSON TOPIC: WORK DONE BY A FORCE When graphing the force on an object vs the distance the object moves, the area is the work done as shown When finding the work done from a graph, we consider it a positive work when the graph is above the x - axis, and negative work when the graph is below the x-axis If the force is not constant, we still find the area under the curve, as this will represent the average force multiplied by the distance LESSON TOPIC: WORK DONE BY A FORCE Sample Problem: A hiker pulls a sled 25 m across a snowy field. The hiker exerts a constant force of 135 N, 48o above the horizontal in pulling the 45 kg sled. If the magnitude of friction between the sled and the ground is 44 N, determine: a) The work done by gravity b) The work done by the normal force c) The work done by the hiker d) The work done by friction e) The total work done on the sled f) What would happen to the total work done on this sled? How would it show up? 3  LESSON TOPIC: TYPES OF ENERGY LEARNING GOALS We will know how to determine the kinetic energy an object possesses, and how the amount of kinetic energy can change with work done on an object. We will know how to calculate the amount of gravitational potential energy an object has relative to a reference point. We will be able to determine the amount of total mechanical energy an object possesses. HW: Pg. 232 #1,2 Pg. 234 #1 Pg. 235 #1 – 5 Mechanical energy falls into 2 categories: 1) Kinetic energy (the energy of motion) 2) Potential energy (the energy an object possesses because of forces in its environment) Kinetic energy increases with the mass of the object, and the speed of the object. Speed of the object (m/s) Kinetic Energy (J) Mass (kg) Sample Problem: Determine the kinetic energy of a 1500 kg car travelling at 36 km/h. Show that the units do give you joules. 4  Start with the work formula, use Newton's 2nd law and the kinematics equation without time to verify that the Sample Problem: horizontal force of 5.0 N over a distance of 0.50 m. What is the puck's speed after this force has been applied? energy that can be converted into kinetic energy when an object falls for example. The more height an object has, the more mass it has, and the stronger the gravitational field where the Gravitational Potential Energy (J) Mass (kg) Gravitational field strength (N/kg (9.8 near earth) Sample Problem: 5 Sample Problem: energy of the student if they are moving at 7.5 m/s at this instant? LEARNING GOALS We will understand that in any energy transformation, there will never be 100% of the desired energy type afterwards - there is always waste. We will be able to use the law of conservation of energy to analyze mechanical energy transformations assuming no losses. Pg. 241 # 1 Pg. 241 # 1 – 3 6 Any of these forms of energy can be transformed into another form - including by machinery / devices or natural processes such as photosynthesis. Example: No matter what the transformation is, there will be always some waste (undesired) energy transformation, but the total before the transformation is the same as the total after the Example: 95 J of thermal energy created. 7 Even though no energy transformation is truly 100% efficient, if we assume there are no losses due to forces such as friction, we can use the law of conservation of energy to analyze mechanical systems. Let's look at a 65 kg diver diving off of a 10 m diving board. Find the gravitational potential Since the total mechanical energy is the same at each location, we can say it was conserved, objects like projectiles, rollercoasters, and other mechanical systems. any snapshot any other snapshot Identify the types of energy at each location you are analyzing and sub them in to the above 8 Sample Problem: a) How fast is it going after it has fallen 15 m? b) How high above the ground is it when it is moving at 22 m/s? LEARNING GOALS We will understand that in any energy transformation, there will never be 100% of the desired energy type afterwards - there is always waste. transformations by determining the useful energy output and energy input. Pg. 243 #1,2 Pg. 249 #1 – 4,6,7 9 transforming devices, so that we can reduce the amount of energy input required, or increase the output. For example, by increasing the efficiency of a lightbulb, we can get the same amount of light energy output, non-renewable sources such as oil, coal, and natural gas. What do you notice about the major waste energy for these transformations? Why do you think the electric heater is so In order to determine the efficiency of a process, you need to identify what the energy input is (this can also following formula. The useful energy output (what we are trying to transform it into) This formula works as The energy that is required long as you have both the transformation energies in the same (what is being transformed) (This is always < 100) units. Sample 1: 10 Sample Problem: What is the efficiency of a rope and pulley system if a painter uses 1.93 kJ of mechanical energy to pull on the rope and lifts a 20.0 kg barrel at constant speed to a height of 7.5 m above the ground? LEARNING GOALS We will understand that power is the rate of change of an energy transformation, or the rate at which work is done. We will be able to calculate the power of an object (such as a student!) We will know how electrical power is communicated, and how Pg. 251 # 1 – 3 Pg. 252 # 1 Pg. 253 #1 Pg. 254 #1,2,4 11 same pickup truck, who does more work? In physics, power describes the rate of an energy transformation, or the rate that work is done. The higher OR 1 W = 1 J/s What type of energy is being transformed, if we move at a constant speed up the stairs? What do we need to measure to determine our power? Record the results below! 12 When it comes to electrical devices, the power rating tells you how much energy the device consumes. The electric company charges you based on how much electrical energy you use. The rate the electric company charges (cents / kWh) The amount you pay (cents) The total electrical This can vary depending on time energy you use (kWh) of day as well... Sample: peak rate of electricity? LEARNING GOALS We will understand what the heat capacity of a substance tells us about energy absorbed or released when that substance changes temperature. We will be able to calculate the heat required to change the temperature of various substances. We will know what happens when a hot object comes into contact with a cold substance, and do calculations using the principle of thermal energy exchange. Pg. 283 #1 – 3 Pg. 286 #1,2 Pg. 287 #1,3,5,7 13 Whenever you heat water up on the stove, you might notice it takes a bit of time to bring the water up to the heat you need to cook your food. The whole time the oven is transferring The reason is these two different substances have different properties, including their specific heat capacity (c). What specific heat capacity tells you is the amount of energy that 1 kg of a substance must absorb in order to increase its temperature by 1 C (or the amount it must release to decrease its temperature by 1 C) For example, 1 kg of water must absorb 4180 J of energy to go up one degree. When glass cools off by 1 degree, 1 kg of it would release 840 J Change in temperature ( C) Δ f Quantity of heat (J) Mass (kg) Specific heat capacity (+) if absorbing energy (J / kg C) ( - ) if releasing energy Example: C to 40.0 C, how much thermal energy is absorbed by the water? 14  When a high temperature object is in contact with a lower temperature object, the hot object same. If we assume that there is no energy lost to the environment, or absorbed from the environment, we can use the following statement: Sample Problem: temperature of 10.0 C. The metal-water combination reaches a final temperature of 15.6 C. Determine the identity of the metal. Sample Problem: During an investigation, 200.0 g of silver is heated to 90.0 300.0 g of ethyl alcohol that has an initial temperature of 5.0 C. Determine the final temperature of the silver-alcohol mixture. 15  LEARNING GOALS We will understand that energy must be absorbed or released whenever a substance changes its physical state. We will recognize what the specific latent heat of vaporization or specific latent heat of fusion tells you about a substance. We will determine the energy absorbed when heating a substance, or the energy released when cooling a substance. Pg. 293 #1 – 3 Pg. 295 #1,3,5,6 matter of the substance. determine the quantity of heat to change state, you must ust the following formulas. Liquid Liquid Gas Q - Quantity of heat (J) Lf - Latent heat of fusion (J/kg) m - Mass (kg) Lv - Latent heat of vaporization (J/kg) 16 17  2467 2700 Sample Problem: Determine the amount of energy released when 2.5 kg of water freezes. Sample Problem: Ethyl alcohol is a liquid at room temperature. How much energy is absorbed when 135 g of ethyl alcohol at 21.5 C is heated until it all boils and turns to vapour? 18 LEARNING GOALS We will understand what atomic number and atomic mass tell us, and what the Bohr - Rutherford Model of the atom looks like. We will also know what an isotope is. We will recognize what forces are responsible for holding the Pg. 322 #1 – 7 Pg. 329 #1 – 3,5,6 One of the more complete models of the atom is the Bohr - Rutherford model. The protons and neutrons are in the nucleus (we call them collectively nucleons) and the electrons orbit in energy shells around the nucleus. Given that this is the section on nuclear physics, we care far more about what is happening with the nucleus 9 protons F 9 electrons 10 neutrons 19 nucleons (protons and neutrons) 9 protons and 9 electrons (in an electrically neutral atom) version of the same element with a different number of neutrons (and therefore atomic mass) but the same number of protons (and therefore atomic number). Carbon-12 and carbon-14. They have the same number of protons (which is why they are carbon) but a different The only exceptions are isotopes of hydrogen. Hydrogen-1 = hydrogen Hydrogen-2 = deuterium Hydrogen-3 = tritium 19 the nucleus stays together even in stable isotopes. In a helium nucleus, there are two protons and two neutrons. Since the the nucleus from flying apart? The answer is another fundamental force of nature called the strong nuclear through this force and it overcomes the repulsive electrostatic force. nucleus becomes unstable. In large nuclei, more neutrons are needed to provide the attractive strong force to counteract the repulsive electrostatic force. That is why as you go up the periodic table, larger elements tend to have more neutrons than protons. than a chemical reaction where atoms are shuffled into new molecules. In a nuclear reaction, the actual particles in the nucleus are often changed, and it can result in new elements being created (called transmutation). Parent nucleus Daughter nucleus + Decay Particle In alpha decay (α - nucleus. The general reaction for an alpha decay is: Sample: 20 Beta-Negative Decay (β- decay) is where an electron is emitted from the nucleus. In order to maintain a conservation of charge, a neutron also decays into a proton in the nucleus. The general reaction for beta-negative decay is: Sample: Beta-positive decay (β+ spontaneously decays into a neutron. The general equation for beta-positive decay is: Sample: 21 Gamma decay often occurs after alpha decay or beta decay has taken place. The nucleus is left in an excited state, and returns to a ground state by emitting energy in the form of a highly energetic photon (a gamma ray). Sample: energetic enough to remove electrons from atoms. If they come into contact with tissue, it can result in as much as possible. Alpha decay is the most energetic, but has little penetrating power so unless you ingest / inhale the substance emitting alpha particles you are likely fine. Beta decay and gamma decay penetrate further and so must be shielded against (usually with lead). 22 LEARNING GOALS We will understand what what the half-life of a substance tells you. We will how to solve problems involving half-life, including solving for the exponent in the equation. We will understand how half-life can be used in carbon dating to determine the age of fossils. Pg. 332 #1,2 Pg. 333 #2 – 6 will take place. Radioactive decay is a statistical situation - with a large enough sample of nuclei in a substance, you can make predictions about how quickly the decay will take place. The half-life of a substance is a way of measuring this. For example, cobalt-60 has a half-life of 5.27 years. What this means is: 2) Looking at an individual nucleus, there is a 50% chance it would have decayed after 5.27 years 4) Every time 5.27 years passes, the amount remaining undecayed is reduced by half. (1, 1/2, 1/4, 1/8, etc) Elapsed time Amount remaining Half-life of the substance after time (t) Original amount 23 Sample: Neon-19 has a half-life of 17.22 s. What mass of neon-19 will remain from a 100 mg sample after 30.0 s? Sample: (Use log.... unless you just love graphing exponential functions...) Carbon dating is a very powerful application of the concept of half-life. When an organism (plant or animal) is living, they consume both isotopes of carbon (carbon-14 and carbon-12) and the ratio between them is consistent and equal in all living things. When the organism dies, the carbon-14 decays, while the carbon-12 does not. The ratio decreases the longer that an organism is dead. Carbon-14 undergoes beta-negative decay with a half-life of 5730 years. By measuring the amount of carbon-14 left in a fossil, scientists can determine the age of that fossil. Sample: How old is a bone if it currently contains 0.39% of the carbon-14 it had when it was living. 24 LEARNING GOALS mass-energy equivalence. We will be able to use the concept of mass-defect in order to determine the binding energy of a nucleus, as well as the energy released in a fission / fusion reaction. Pg. 336 #1 Pg. 338 #1 Pg. 341 #2 - 4 Pg. 344 # 1 Pg. 347 #1 – 3,6ab is accepted as mass-energy equivalence, and described by the well known equation: The speed of light in a Energy (J) vacuum (3.0 x 10 m/s) Mass (kg) This allows the 2 conservation laws (mass and energy) to be combined into a single conservation law of mass-energy: system remains constant. What this means is if you appear to 'lose' mass in a process, it isn't lost - it just has turned into energy instead. We use the concept of this mass defect in order to determine the binding energy of nuclei, as well as to determine the energy released in a fission or fusion reaction. The units of J and kg are far too large when talking about nuclear reactions, so we use atomic mass units (u) for mass and mega-electron volts (MeV) for energy instead. Before you sub them into the above 1 u = 1.66 x 10 kg 1 MeV = 10 eV = 1.602 x 10 25  The nucleus is very difficult to break apart. If you want to remove all of the nucleons from the nucleus you must provide an amount of energy equal to the binding energy of the nucleus. This binding energy is a result of the fact that a nucleus has less mass than it is supposed to if you add up all of its components. Sample: Determine the binding energy of a lithium-7 nucleus, given that its actual mass is 7.01600 u There are two types of nuclear reaction where the products of the reaction have less mass than the reactants Fission: Occurs in large nuclei Is the breaking of a nucleus into smaller nuclei What we currently use in our powerplants Fusion: Usually involves smaller nuclei Is the fusing of two nuclei together into a larger nucleus The process taking place in any star (our sun is fusing H into He, and releasing a ton of energy) What we would love to use in our powerplants, but right now it takes more energy to make the reaction happen than we would get out of it. 26 drive a generator to produce electricity (any power plant that burns fuel like coal or natural gas does the same thing). In Canada we have CANDU reactors in our nuclear plants. Natural uranium is used as a fuel, and once the reaction starts, it is a chain reaction that can be slowed down / stopped using control rods. Heavy water is used to both absorb the thermal energy in the reaction, and moderate the reaction. This heavy water then heats normal water to create steam and drive the turbine. The heavy water cools off from this and goes back into the reactor to again Cadmium control rods are inserted to slow the reaction down or Sample Problem: 27 Sample Problem: 28