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HEAT, FORCE, MOTION, ELECTRICITY, MAGNETISM, SOUND, LIGHT Today is the LAST day of Notes! ...As long as you behave tomorrow & Friday!! Heat & Phase Changes What happens to the speed of the particles in gases as they are exposed to freezing temperatures? They slow down What happens if a liquid is vaporized? It turns into a gas Phase Change Graph Heat Phase Change Graph Heat Phase Change Graph Heat Phase Change Graph Heat Phase Change Graph Heat Phase Change Graph Heat Phase Change Graph Conduction, Convection, Radiation This website I’m going to show you is linked on my website…www.schoolrack.com/a browder Thermal Expansion Alcohol & mercury are liquids that are used in thermometers…why? Both expand at predictable rates when heated What do you feel as you drive across the James River Bridge? Why? Expansion joints are put on bridges because the concrete expands & contracts when what happens? The temperature changes Speed At what speed would a bus have to move in order to travel 40 kilometers in two hours? What is the formula for speed? Speed = Distance ÷ Time Speed = 40 km ÷ 2 hr 20 kilometers/hour Work What is the definition of work? • The scientific definition of work = using a force to move an object a distance ▫ …when both the force and the motion of the object are in the same direction Work requires motion…If there’s no motion, there is no work being done Which of the following is work? A lamp hanging from a ceiling A man pushing against a concrete wall A car being towed down a street A rocket drifting through space Which of the following is work? A lamp hanging from a ceiling A man pushing against a concrete wall A car being towed down a street A rocket drifting through space Mechanical Advantage A large cart on wheels full of bird seed mix that needs to be moved onto a moving truck could be moved either by lifting it above the ground and setting it onto the truck platform or by using an inclined plane. The advantage of using the inclined plane is that the work can be done – A. more quickly B. with less friction C. using less force D. using less energy Mechanical Advantage A large cart on wheels full of bird seed mix that needs to be moved onto a moving truck could be moved either by lifting it above the ground and setting it onto the truck platform or by using an inclined plane. The advantage of using the inclined plane is that the work can be done – A. more quickly B. with less friction C. using less force D. using less energy Mechanical Advantage A truck manufacturer reduces the mass of a car by 350 kg. If the new design is otherwise identical to the old design, how will the new truck compare to the old truck? A. It will have a greater gravitational attraction to the road. B. It will require more fuel to operate C. It will need less force to move D. It will release more gas emissions Mechanical Advantage A truck manufacturer reduces the mass of a car by 350 kg. If the new design is otherwise identical to the old design, how will the new truck compare to the old car? A. It will have a greater gravitational attraction to the road. B. It will require more fuel to operate C. It will need less force to move D. It will release more gas emissions Power P = w/t To finish a project 500,000 Joules of work are needed. The time taken to complete the project is 50 seconds. How much power is needed? Power = 500,000J ÷50 sec 10,000 J/sec Simple Machines A wheel & axle is a lever that rotates around a fixed point. All of the following machines employ a wheel & axle except a – A. Bicycle B. Skateboard C. Pencil sharpener D. Crowbar Simple Machines A wheel & axle is a lever that rotates around a fixed point. All of the following machines employ a wheel & axle except a – A. Bicycle B. Skateboard C. Pencil sharpener D. Crowbar What type of simple machine is a crowbar? Lever! Static Electricity What are some examples of static electricity? A balloon sticks to a wall after it is rubbed with a piece of wool. Laundry in a clothes dryer sticks together because it becomes charged with static electricity. The electrons are transferred as clothes rub against each other in the dryer When I comb my hair, the hair appears to be attracted to my comb. My hair and the comb must have what type of charges? Unlike charges Current Electricity Direct Current vs. Alternating Current Direct Current = (DC) electric current that flows through a wire in only one direction Example = current that flows through batteries Alternating Current = (AC) electric current that reverses its direction regularly Example = used to run appliances Kinds of Electricity Static Current • An electric charge that collects or builds up on the surface of an object • The flow of electric charges carried through a material such as wire or other conductors • Examples – Shocking – Lightening • Examples – Power lines – Computers – Appliances What Is Static Electricity? • A stationary electrical charge that is built up on the surface of a material Conductors and Insulators Conductors • Any material that allows electric charges to move through it • Examples: – Metals (esp. copper) – Your body – Electric wires Insulators • Materials that do not allow electric charges to flow freely through them • Examples: – Wood – Glass – Rubber Simple Circuits • Series circuit – All in a row – 1 path for electricity – 1 light goes out and the circuit is broken and all the lights go out. – Shares voltage; current stays the same across circuit. – Ex: Old Christmas Lights • Parallel circuit – Many paths for electricity – 1 light goes out and the others stay on – Shares current; voltage stays the same across circuit. – Ex: Your house, power lines Series Circuits Single Path for Current to Flow Parallel Circuits Often missed question…, but you’re gonna ace it next week! Correct answer = F 1 Magnetism Magnetism is the attraction of a magnet for another object. A magnetic pole is the area of a magnet where the magnetic effect is strongest. Electromagnets Electromagnets are strong temporary magnets. Magnetism can be turned on and off Made by wrapping a wire around a piece of iron and sending a current through the wire. Magnetic field is in the same direction as the electric current. Strength of Electromagnets There are several ways to increase the strength of an electromagnet: Increasing the voltage or current Increasing the number of loops of wire Make the loops of wire tighter Increase the number of nails in the core Use iron for the core Waves crest wavelength amplitude trough Identify each of the labeled parts of the wave above. Identify Compression, Rarefaction, & Wavelength A = Nothing B = Wavelength – the distance between one point on a compression and the corresponding point on the next compression in a sound wave C = Compression – the part that’s squished together D = Rarefaction – the part that’s spread out What is Sonar? Uses sound waves to measure the distance between objects underwater • Sonar – Sonar is a system of detecting reflected sound waves. – The sonar device measures the time it takes to detect the reflected sound waves. Which travels faster, sound or light? Light travels faster than sound. You see the fireworks before you hear them You see the lightning before you hear the thunder Light The reason we see things with our eyes is because light is reflected Reflection of Light Angle of incidence = Angle of reflection What property of light causes this pencil to appear bent? Refraction – because light travels slower through water than through air