How Do We Make It Work? PDF

HOW DO WE MAKE IT WORK?  GLOBAL CONTEXT: Scientific and Technical Innovation RELATED KEY CONCEPT: CONCEPTS: Connection Form, Transformation Global Exploration: Principles, and discoveries SOI: Machines have...

HOW DO WE MAKE IT WORK?  GLOBAL CONTEXT: Scientific and Technical Innovation RELATED KEY CONCEPT: CONCEPTS: Connection Form, Transformation Global Exploration: Principles, and discoveries SOI: Machines have revolutionized life by making it easier to change energy from stored forms to movement and back again. HOW DO WE MAKE IT WORK? OBJECTIVES: 1. Define the term FORCE. 2. Differ between types of forces. 3. Define contact force, contactless force. 4. Discuss normal ,Friction, tension and compression as contact force. 5. Discuss Gravity, air resistance and magnetism as contactless force. 6. Differ between mass and weight. 7. Discuss vector and scalar. 8. Define types of energy 9. State the energy transfer in real life. 10. Discuss the main 6 simple machines WHAT IS SCIENCE ? THINK …PAIR …AND SHARE ! What is science? WHAT IS FORCE?  Force formula Newtons second law Remember the terms proportional vs inversly Starter: WHAT CAN A FORCE DO ? Take A min to think with a partner Exit Slip  Understanding normal force effect If we have 2 ice blocks with 5 kg as mass , one is stationary and one is in constant velocity sliding over ice so friction is zero, the object force is equal to 9.8*5 N downward. What makes the object stay in place ? 5 KG 5 KG Constant stationary velocity CON. Without normal force these objects will sink down the ice surface with force of 48 N, but the normal force acting in opposite direction to the gravity leads the objects to stay in place. Normal force : It is always perpendicular to the surface in contact. Contact force , Tension vs Compression Tension is to stretch , pull a robe in both sides Compression is the force that shortens an object together ( compress) Examples on tension force Examples on compression force Think … Compression or Tension Bending a book A compression and tension force at the same time COMPLETION …CONTACT FORCES  Friction, air resistance, water resistance and buoyancy (upthrust) are all examples of contact forces.  A contact force occurs when the objects are touching. Water resistance Swimmers force  FRICTION Discuss P.26 AIR RESISTANCE Discuss P.26/ car parachute WATER RESISTANCE Water resistance Swimmers force BUOYANCY NON-CONTACT FORCES  Gravity, magnetism and electrical forces, such as electrostatic, are examples of non-contact forces.  A non-contact force occurs when the objects are not touching. For better understanding for the non contact force , we use the idea of a field. MAGNETISM ELECTRICAL FORCE GRAVITY Discuss and write everything you know about , mass , weight and gravity.  Mass vs weight In everyday language, we use the term weight when we are often describing mass. In science, there is a clear difference in what these two words refer to. Scalar vs Vector Discuss Balanced forces on P.32 Terminal velocity ( What happens when objects fall?) It is a special case of force balancing , it is the speed at which a falling object accelerate. At terminal velocity, the forces of weight and air resistance are balanced. Discuss P.33 Group Work EXPERIMENT P.34  Take a minute practice ☺ Solve given worksheets about balanced and unbalanced forces. What is work? Answer questions P.47 What is energy ? Energy is the capacity for doing work. Measured by JOULE (a force of 1 N is applied over a distance of 1 m)  With your group Discuss the law of conservation of energy.  Potential energy Potential energy A type of energy is stored and waiting to be released. Chemical potential energy Is stored in chemical elements or compounds and released as endo or exothermic reactions. Gravitational potential energy A form of energy stored by lifting an object upwards against gravity, it is released when the object falls. Elastic potential energy A form in energy in a stretching or compressing springs or rubbers. Discuss P.57  Kinetic energy Kinetic energy A type of energy is possessed by moving objects Comment Discuss and give examples on sound energy Identify energy transfers P.60 What’s the Connection? ? energy stores Different Energy Stores chemical kinetic gravitational potential thermal elastic  Different Energy Stores: Transfers When you eat food, this is a chemical store. You transfer the energy into different stores. Kinetic stores: when you move. Thermal stores: to maintain your body temperature. Chemical stores: when you make different compounds in your body.  Different Energy Stores: Transfers Now we know the 5 different energy stores. Energy can be transferred between stores as electric, light, sound or mechanical (when a force acts on the object). For example, a battery operated fan. The energy stores Energy is transferred move from chemical as electrical energy. to kinetic.  Remember! Energy Stores chemical thermal kinetic gravitational potential elastic Energy Transfers electric light sound mechanical (a force is acting on the object)  Energy Transfer Experiments Energy the Start Answers Energy Store at Energy Store at the End Transfer lighting a candle chemical thermal light battery operated chemical thermal light torch toy car rolling gravitational kinetic sound down a ramp potential pendulum gravitational kinetic mechanical potential hair dryer chemical kinetic sound (burning fuel at power station simple circuit chemical thermal electrical Newton’s cradle gravitational kinetic sound potential  Quick Assessment: Different Energy Stores Match the images below to their energy store. chemical burger kinetic cheetah gravitational potential parachute thermal candle elastic rubber bands  Assessment What is the main energy transfer taking light place in a solar powered calculator? (1 mark) chemical What are the energy stores involved when using a camping stove? (2 marks) thermal Energy stores: chemical (at the power station); What are the energy stores and pathways thermal. involved when turning on an electrical Energy transfers: radio? (3 marks) electrical and sound.  The Law of Conservation of Energy What do you think this is? In pairs, you have 2 minutes to come up with an explanation. Share your idea with the pair working next to you. Do they have any different ideas? Do you want to change your explanation? The Law of Conservation of Energy ‘Energy cannot be created or destroyed, but is transferred from one store to another.’ In all of the experiments, there was an energy store at the beginning and an energy store at the end. The only thing that changed was the amount of energy in the stores. The Law of Conservation of Energy ‘Energy cannot be created or destroyed, but is transferred from one store to another.’ Copy the title and law into your book. Choose one of the experiments and explain how it reflects the Law of Conservation of Energy. Sum It Up! Sum up today’s lesson using 5 keywords. Homework: Energy Stores and Transfers in the Home Go around your home and choose 5 Extension: Can you find examples different devices. For each one, state that include all the different types of the energy stores and energy energy stores and energy transfers? transfers. Energy Circus STATION 1 A car rolls down a ramp. Start Point: The car is held End Point: The car is rolling down stationary at the top of the ramp. the ramp. pathway: _______________________ mechanically car raised in Earth’s moving car gravitational field store: _______________________________ gravitational potential store: _______________________________ kinetic STATION 1 A car rolls down a ramp. Start Point: The car is held End Point: The car is rolling down stationary at the top of the ramp. the ramp. The energy associated with the gravitational potential store has decreased. The energy associated with the kinetic store has increased. The total energy in the system has stayed the same. STATION 2 A spring toy is pushed down on the bench to compress it and is then released. Start Point: The spring toy is End Point: The toy is at the highest compressed. point of its jump. pathway: _______________________ mechanically spring toy raised in compressed spring Earth’s gravitational toy field store: _______________________________ elastic potential store: _______________________________ gravitational potential STATION 2 A spring toy is pushed down on the bench to compress it and is then released. Start Point: The spring toy is End Point: The toy is at the highest compressed. point of its jump. The energy associated with the gravitational potential store has increased. The energy associated with the elastic potential store has decreased. The total energy in the system has stayed the same. STATION 3 A bouncy ball is dropped from a height. Start Point: The ball is held End Point: The ball is compressed stationary above the ground. as it hits the floor. pathway: _______________________ mechanically ball raised in Earth’s compressed ball gravitational field store: _______________________________ gravitational potential store: _______________________________ elastic potential STATION 3 A bouncy ball is dropped from a height. Start Point: The ball is held End Point: The ball is compressed stationary above the ground. as it hits the floor. The energy associated with the gravitational potential store has decreased. The energy associated with the elastic potential store has increased. The total energy in the system has stayed the same. STATION 4 A crisp is set on fire. Start Point: The crisp has just End Point: The crisp has burnt and been lit. the flame has gone out. _______________________ pathway: heating via radiation crisp environment pathway: _______________________ heating via particles store: _______________________________ chemical store: _______________________________ thermal STATION 4 A crisp is set on fire. Start Point: The crisp has just End Point: The crisp has burnt and been lit. the flame has gone out. The energy associated with the chemical potential store has decreased. The energy associated with the thermal store has increased. The total energy in the system has stayed the same. STATION 5 A battery-powered torch is switched on. Start Point: The torch is off. End Point: The torch is on. pathway: pathway: heating via ______________ battery _____________ electrically bulb radiation ___________ environment store: _______________ chemical store: _______________ thermal store: _______________ thermal STATION 5 A battery-powered torch is switched on. Start Point: The torch is off. End Point: The torch is on. The energy associated with the chemical store has decreased. The energy associated with the thermal store has increased. The total energy in the system has stayed the same.  Learning Objective To calculate changes in energy. Success Criteria To apply the equation for elastic potential energy. To recall and apply the equations for kinetic energy and elastic potential energy. To recall and apply the equations for gravitational potential energy, kinetic energy and elastic potential energy.  What’s the Connection? Energy It is possible to calculate the following: the kinetic energy stored by a moving object, such as a bicycle; the elastic potential energy stored in a stretched spring, such as in a bow; and the amount of gravitational potential energy gained by a raised object, such as a diver on a board. Key Words energy; gravitational potential energy; elastic potential energy; kinetic energy  Elastic Potential Energy elastic potential energy = ½ x spring constant x (extension)2 Or Ee = ½ke2 Ee = elastic potential energy in J k = spring constant in N/m e = extension in m  Elastic Potential Energy Using the equation Ee = ½ke2, calculate an archer’s elastic potential energy when his spring constant is 8N/m and his extension is 0.75m. Ee = ½ x 8 x 0.752 Therefore, Ee = 2.25J (to two decimal places)  Kinetic Energy Kinetic energy = ½ x mass x (speed)2 Or Ek = ½mv2 Ek = kinetic energy in J m = mass in kg v = speed in m/s  Kinetic Energy Using the equation Ek = ½mv2, calculate the kinetic energy of a cyclist when her speed is 7.27m/s, her bicycle’s mass is 11kg and her mass is 50kg. Ek = ½ x 61 x 7.272 Therefore, Ek = 1612.01J (to two decimal places)  Gravitational Potential Energy GPE = mass x gravitational field strength x height Or Ep = mgh Ep = gravitational potential energy in J m = mass in kg g = gravitational field strength in N/kg h = height in m  Kinetic Energy Using the equation Ep = mgh, calculate the gravitational potential energy of a diver when his mass is 60kg, his gravitational field strength is 10N/kg and he jumps from the 10m platform. Ep = 60 x 10 x 10 Therefore, Ep = 6000J ENERGY TRANSFER We can calculate energy transfer by using the equation Energy transfer =Power x time IT is measured in JOULE  Energy Equations Elastic potential energy: Ee = ½ke2 Tick these off your Kinetic energy: Ek = ½mv2 Required Equations Gravitational potential energy: Ep = mgh Sheet. Use these equations to help you complete the Calculating Energy Activity Sheet.  Question 1 When a stationary object has been lifted, more energy is stored in the… A. elastic potential store. B. electrostatic store. C. gravitational potential store. D. kinetic store.  Question 2 When a stationary object has been compressed, more energy is stored in the… A. elastic potential store. B. electrostatic store. C. gravitational potential store. D. kinetic store.  Question 3 The energy store of a moving object is its… A. chemical store. B. electrostatic store. C. gravitational potential store. D. kinetic store.  Question 4 When a system changes, the total amount of energy… A. decreases. B. increases. C. is conserved. D. is dissipated WHAT IS A SIMPLE MACHINE? A simple machine changes the direction or size of a force. It makes it much easier to pull or push something over a longer distance. HOW MANY SIMPLE MACHINES ARE THERE? There are six types of simple machines: levers screws wheel and axles inclined planes pulleys wedges LEVER Levers are everywhere in our daily life and examples include: see-saws oars wheelbarrows scissors LEVER Effort Load Beam Fulcrum Examples of objects that use levers, include seesaws, oars, wheelbarrows and scissors. WHEEL AND AXLE This type of simple machine is the most common. Wheels cannot work without axles. Wheel Wheel Axle Axle Force is used to turn the wheel, which then causes the axle to turn. Examples of wheels and axles being used in everyday life include screwdrivers, skateboards and doorknobs. PULLEY A pulley is a rope or chain with a wheel and axle attached. Using a pulley means that heavy loads can be lifted without much effort. Examples of objects that use pulleys include lifts, cranes and wells. SCREW A simple machine that uses a screw allows something to move from a lower position to a higher position by moving it in a circle. Examples of screws in everyday life are: a jar lid a tap a drill the end of a lightbulb INCLINED PLANE Some simple mechanisms use an inclined plane. Inclined means sloping. On an inclined plane, one end is lower than the other end. This allows things to travel from the higher end to the lower end, or vice versa, with little effort. There are inclined planes all around us, such as: slides ladders ramps INCLINED PLANE Inclined plane WEDGE A wedge can be used to separate an object. It is usually triangular shaped. An example of this is an axe, which is two inclined planes. Wedges can also hold things together and stop them from moving. Example include: staples nails doorstops Can you remember the six simple machines? A CLAW HAMMER LIFTING A NAIL IS AN EXAMPLE OF A… lever screw Keep thinking pulley Keep thinking Next Question Next Question  WHICH OF THESE WOULD BE BEST FOR KEEPING A DOOR OPEN? screw Keep thinking pulley Keep thinking wedge Previous Question Next Question Previous Next Question Question  WHICH OF THESE WOULD BE BEST TO MOVE A WHEELBARROW UP A SLOPE? inclined plane (ramp) pulley Keep thinking screw Keep thinking Previous Question Next Question Previous Next Question Question  IT TAKES LESS EFFORT OR WORK TO WALK UP A RAMP RATHER THAN STEPS TO THE SAME HEIGHT. True False Keep thinking Previous Question Next Question Previous Next Question Question  A IS A SIMPLE MACHINE USED TO INCREASE LIFT STRENGTH WITH A TRACKED WHEEL AND A CORD, ROPE OR CHAIN. screw Keep thinking pulley wedge Keep thinking Previous Question Next Question Previous Next Question Question  A KNIFE AND A CHISEL ARE EXAMPLES OF A… screw Keep thinking wedge pulley Keep thinking Previous Question Next Question Previous Next Question Question  THE WHEEL AND AXLE SYSTEM IS AN EXAMPLE OF… a complex machine Keep thinking a simple machine an inclined plane Keep thinking Previous Question Next Question Previous Next Question Question  WHICH OF THESE IS NOT A WEDGE? axe Keep thinking pulley nail Keep thinking Previous Question Next Question Previous Next Question Question  ELEVATORS WORK BY USING A POWERFUL SYSTEM. wedge Keep thinking screw Keep thinking pulley Previous Question Next Question Previous Next Question Question  A SCREW CAN BE THOUGHT OF AS… an inclined plane wrapped around a rod a lever Keep thinking a wedge Keep thinking Previous Question Next Question Previous Next Question Question  SOME OF YOUR TEETH ARE SHAPED LIKED WEDGES? True False Keep thinking Previous Question Next Question Previous Next Question Question  WHICH OF THESE STATEMENTS ABOUT WEDGES IS INCORRECT? Wedges can split things. Keep thinking Wedges can rotate things. things Wedges are a simple Keep thinking machine. Wedges can cut things. Keep thinking Previous Question Next Question Previous Next Question Question  WHICH IS NOT AN EXAMPLE OF A SCREW? corkscrew Keep thinking nut and bolt Keep thinking Guillotine (paper guillotine (paper cutter) cutter) Previous Question Next Question Previous Next Question Question  A WOOMERA (SPEAR THROWER) ACTS AS A TO MOVE THE SPEAR WITH FORCE AND SPEED. pulley Keep thinking lever screw Keep thinking Previous Question End of quiz Previous End of quiz Question