RSS Science 10 Pre-AP Fall 2024 U4L1 DRTs NOTES Working with Energy PDF

## WORKING WITH Energy **Hint** _Comic is from www.amureprints.com._ **RSS Science 10 Pre-AP with Dr. T, Fall 2024, U4L1** Name: Date: Block: **embers - One Objibway's Meditations** STARTED MY DAY shoveling eight inches of fresh overnight snow, and it's still falling. The beauty of that is the q...

## WORKING WITH Energy **Hint** _Comic is from www.amureprints.com._ **RSS Science 10 Pre-AP with Dr. T, Fall 2024, U4L1** Name: Date: Block: **embers - One Objibway's Meditations** STARTED MY DAY shoveling eight inches of fresh overnight snow, and it's still falling. The beauty of that is the quiet you fall into through a deliberate, conscious act, the mindful joy of watching your energy change things, of feeling your spirit come alive in the effort and sheer bright-white light of joy that comes from seeing a clear and open path to your home - the place where your dreams reside. * Richard Wagamese (p. 27) **Today's Goals** To be able to: - discuss the eurocentric definition energy - discuss potential versus kinetic energy - state the Law of Conservation of energy - identify different types of energy transformations - appreciate the importance of energy transformations - explore different worldviews of energy and their implications - perform energy calculations with respect to kinetic energy, gravitational potential energy, and energy efficiency; $elastic potential energies$ **Exploring Further** - YOUTUBE: Indigenous Knowledge and Western Science: Dr. Leroy Little Bear Talk (21:32) - The CBC Massey Lectures: The Truth About Stories - Part 1, by Thomas King (54:52) (on Creation Stories and Worldviews, amongst other things, humourous) - Bozeman Science: Definitions of Energy (7:56) at https://www.youtube.com/watch?v=DGVtH5xmb9M **What is energy?** - In Aboriginal philosophy, existence consists of energy. All things are animate, imbued with spirit, and in constant motion. In this realm of energy and spirit, interrelationships between all entities are of paramount importance, and space is a more important referent than time. - Dr. Leroy Little Bear (p.77, Jagged Worldviews Colliding) - In Eurocentric science... energy is the ability to do work (W) $W = F \times d$ Where * W is work in Newtonometers (Nm) * F is force in Newtons (N) * d is distance in (m) **Two Main Classes of Energy** | Potential Energy | Kinetic Energy | | ------------- | ------------- | | potential is energy that is stored and has the potential to be "released" or transformed to do work | kinetic is energy that is actually doing work as it is causing matter to move | | | RECALL: W = F x D and to move any matter, in any direction, requires kinetic energy | **Some sub-classes of Potential ENERGY are:** - chemical energy = energy stored in the bonds of molecules - nuclear energy = energy stores in the nuclei of atoms - gravitational energy = energy stored in and related to an objects height above Earth - elastic energy = energy stored in elastic objects such as rubber bands, rubber balls, metal springs **Some sub-classes of Kinetic ENERGY are:** - kinetic energy = energy due to the motion of an object - electric energy = energy due to the movement of charges - thermal energy (aka heat energy) due to the vibration of particles - Solar energy (aka light energy) due to photons traveling in electromagnetic waves - Sound energy = energy transferred as a wave that causes objects to vibrate **Sources of Energy Can Be Classified AS...** - **Renewable energy sources** * Solar Energy * Hydropower Energy * Energy * The Fuel of Life * Biomass Energy * Wind Energy * Geothermal Energy - **Non-renewable energy sources** * Fossil Fuel Oil * Coal * Energy * The Fuel of Life * Nuclear * Natural Gas **Law of Conservation of Energy** Energy can neither be created nor destroyed, it can only be transformed **Examples of Energy Transformations** - chemical -> kinetic (Mechanical) - solar -> chemical - electrical -> thermal **Energy Transformations and The Law of Conservation of Energy** Transformations are never 100% efficient, so we say energy is "lost" to other forms $$ E_{eff}= \frac{E_{out}}{E_{in}} \times 100 $$ **A Little Algebra Reminder** - You have been doing algebra since elementary school: * 3 + 2 = * 3 + 2 = * 3 + 2 = ? * 3 + 2 = y - All of the above are the same. We are now just using a letter (variable) to hold the space of the value that is unknown or changing. - Same with: * 3 + = 8 * 3 + = 8 * 3 + ? = 8 * 3 + y = 8 - Now you probably know how to isolate for the variable if given the equation $$ \frac{3y}{8}=24 $$ Recall $ \frac{3}{8}=24 \div 3$ - But if you look at the isolating the variable for every single equation you have ever solved you should begin to see that there is a pattern or a shortcut, namely: * Do the opposite operation on the opposite side! - And because isolating is essentially working backwards, do: * SAMDEB **Why is an algebra reminder important?** - Because much of science is about representing and predicting the real world using mathematical models. - In other words, much of science is just _math in motion_. **So how do we use formulas to solve problems?** - First you must pick the correct _formula_, also called an _equation_. - To do this, we will learn an approach to solving word problems that can help us in physics and beyond called _Draw and its Vari ESE_, which means: 1. Draw out the problem 2. Label all the _variable (Var)_, known and unknown 3. Find the _Equation_ that links the variables. 4. _Substitute_ in the known variables' values. 5. _Evaluate_ (aka solve) for the unknown variable. **Let's Try!** - Example: How much work does Smudge, one of Dr. T's cats, do if he uses 0.275 N of force to move his toy mouse 6.2 m? * Draw Smudge and mouse * Vari * W = ? * F = 0.275 N * d = 6.2 m * E * W = F.d * W = 0.275 N. 6.2 m * S * E *W = 1.71 N-m **Google** * Sub = "Control"""" * Sup = "control"". **Some Important Energy Equations** 1. **Gravitational Potential Energy** $$PE_{g} = mgh$$ Where: * $PE_{g}$ represents the potential energy due to gravity measured in Joules (J) * m represents the mass of the object in kilograms (kg) * g represents the acceleration due to gravity measured in meters per seconds squared (m/s²) on Earth 9.8 m/s² * h represents the height that the object is falling (m) - Example: Wile E. Coyote wants to make the Roadrunner go splat. He has placed a 374 kg boulder at the edge of a cliff that is 63 meters above the canyon floor. How much potential energy does the boulder have? * Draw Wile E. Coyote and boulder * Vari * M=374kg * h=63m * PE: ? * g=9.8m/s² * E *PEg = ngh * S * E *PEg = 374 kg. 9.8m/s². 63m *PEg = 230907.6 kg * m² / s²renamed Joules *PEg = 231000 J 2. **Elastic Potential Energy** $$PE_{e} = ½kx² $$ Where: * $PE_{e}$ represents the potential energy due to elasticity measured in Joules (J) * k represents the spring constant of an object measured in Newton per meter (N/m) * x represents the displacement of the spring or elastic (how far it is stretched or compressed from its original position) (m) - Example: Wile E. Coyote wants to go faster so he can catch the Roadrunner. He has purchased THE SLINGSHOTINATOR ® from ACME and plans to launch himself at the Roadrunner. How much potential energy will he have if the slingshot has a spring constant of 700 N/m and he is able to displace it by 3.2 m? * Draw Wile E. Coyote with slingshot * Vari * K=700 N/M * PE=? * X=3.2m * E *PE = ½kx² * S * PE = ½.700 N/m.(3.2m)² * PE = 3584 N*m * PE = 3580 J 3. **Kinetic Energy** $$KE = ½mv² $$ _KE is also used as variable for kinetic energy_ Where: * KE represents the kinetic energy of the moving object measured in Joules (J) * m represents the mass of the moving object in in kilograms (kg) * v represents the velocity of the moving object in meters per second (m/s) - Example: How much kinetic energy does Wile E. Coyote have if he is traveling at 19 m/s and has a mass of 18 kg? * Draw Wile E. Coyote running * Vari * KE or kE=? * V = 19 m/s * M = 18 kg * E * KE = 1/2 mu² * S * KE = 1/½. 18 kg. (19 m/s)² * KE = 3249 kg * m² / s² * KE = 3250 J 4. **Energy Efficiency** $$%E_{eff}= \frac{E_{out}}{E_{in}} \times 100$$ Where: * %Eeff represents the efficiency of the energy transformation as a percent * Eout represents the energy output measured in Joules (J) * Ein represents the energy input measured in Joules (J) - Example: When Wile E. Coyote calculated his elastic potential energy from the ACME's MEGASPRING LAUNCHER he anticipated the elastic potential energy to be 15600 J but when he calculated his actual kinetic energy it was only 8700 J. What was the energy efficiency of his spring launched flight? * Draw Wile E. Coyote and slingshot * PEc = 15600 J = input or Ein * KE = 8700 J = output Eout * %Eeff = Eo/Ei x 100 * %Eeff = 8700 J / 15600 J x 100 * %Eeff = 55.8 % efficiency **Unit Conversion Reminder** - When we are doing physics equations, we must use the SI units (International System of Units). - Any units not in the SI form must be converted using unit conversions. - For energy equations we generally: * Convert mass to kg (kilogram) * Convert distances to m (meter) * Convert time to s (seconds) * Convert energy to J (Joule) **Unit Conversion Practice:** - An average roadrunner weighs 0.38 kilograms. To survive a coyote should eat about 3 pounds a day. If Wile. E is only eating roadrunners, bones and all, how many roadrunners should Wile. E. consume per day? There are 2.2 pounds a kilogram. 1. $0.38 \frac{kg}{RR} \times \frac{2.2 lbs}{1 kg} = 0.836 \frac{lbs}{roadrunner} $ 2. $3\frac{lbs}{day}\times \frac{1 RR}{0.836 lbs}= 3.59 \frac{RR}{day}$ **Putting It All Together** - Example: Wile E Coyote has perched a 95 kg boulder at the edge of the cliff, 173 feet above the canyon floor. When he pushed the boulder off the edge reached an average velocity of 27 m/s. What was the efficiency of his energy transformation? * Draw Wile E. Coyote and boulder * M=95kg * h = 173 feet x 0.305 m/ 1 ft = 52.765 m * V = 27 m/s * g = 9.8 m/s² * Eeff = ? = Eo/Ei x 100 is KE/PEg. * Simplify, the Math first * Eeff = Eo/Ei x 100 = KE x 100/PEg = 1/2mv² x 100 / mgh * Eeff = 1/2V² x 100 / gh * Eeff = 1/2(27m/s)² x 100 / 9.8 m/s². 52.765m * Eeff = 364.5 m²/s² x 100 / 517,097 m²/s² x 10^8 * Eeff = 70.5 % eff