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Objective 5: IPC Physics (4A) Calculate speed, momentum, acceleration, work, and power in systems such as in the human body, moving toys and machines. A 1-kilogram ball has a kinetic energy of 50 joules. The velocity of the ball is — F 5 m/s G 10 m/s H 25 m/s J 50 m/s Velocity equations: d v t v f vi a t p mv 1 KE mv 2 2 4(A) QUANTITIES AND UNITS Quantity Symbol Unit mass m kg (kilogram) time t s (second) distance x m (meter) speed or velocity v m/s momentum p kg-m/s acceleration a m/s2 work W J (Joules) power P W (Watts) A 0.50 kg ball with a speed of 4.0 m/s strikes a stationary 1.0 kg target. If momentum is conserved, what is the total momentum of the ball and target after the collision? A 0.0 kgm/s B 0.5 kgm/s C 1.0 kgm/s D 2.0 kgm/s THE LAW OF CONSERVATION OF MOMENTUM states that: Total momentum before a collision Equals Total momentum after a collision What is the net force exerted on a 90.0 kg race-car driver while the race car is accelerating from 0 to 44.7 m/s in 4.50 s? F 9.8 N G 20 N H 201 N J 894 N Use the formulas for a and F to solve for F. F ma a v f vi t Starting from rest at the center of a skating rink, two skaters push off from each other over a time period of 1.2 s. What is the force of the push by the smaller skater? F 16 N G 32 N H 88 N J 100 N (4B) Investigate and describe applications of Newton’s laws such as in vehicle restraints, sports activities, geological processes, and satellite orbits A hockey player pushed a puck toward the opposite side of a level ice rink. The player expected the puck to continue all the way across the ice, but the puck slowed and stopped before reaching the other side. Which of these best explains why the puck failed to slide all the way to the opposite side? F The puck’s temperature changed. G An upward force acted on the puck. H The puck’s momentum remained unchanged. J An opposing force acted on the puck. Newton’s Laws of Motion Law of Inertia An object at rest or in motion will stay that way until a force acts on it. Law of Acceleration An object will accelerate when a force acts on it. Law of Action and Reaction For every action, there is an equal and opposite reaction. (4B) QUANTITIES AND UNITS Quantity Symbol Unit mass m kg (kilogram) acceleration a m/s2 force F N (Newtons) ; 6 3 0 The pictures show how an air bag functions in a collision. How much momentum in kg m/s does the air bag absorb from the crash-test dummy if all of the crash-test dummy’s momentum is absorbed by the air bag? Record and bubble in your answer to the nearest whole number on the answer document. A substance with a lower density will float on a substance with a higher density. Dice = 0.897 g/mL Dwater = 1.00 g/mL Dalcohol = 0.802 g/mL When the air is released from a balloon, the air moves in one direction, and the balloon moves in another direction. Which statement does this situation best illustrate? F What goes up must come down. G For every action there is an equal and opposite reaction. H The shape and size of an object affect air resistance. J The acceleration due to Earth’s gravity is 9.8 m/s2. (4D) Investigate and demonstrate [mechanical advantage and] efficiency of various machines such as levers, motors, wheels and axles, pulleys, and ramps. The Six Simple Machines (4D) QUANTITIES AND UNITS Wout Eff Win Fout d in M . A. Fin d out Quantity Symbol Unit work W J (Joules) mechanical advantage M. A. No unit efficiency eff No unit % efficiency % eff % Which configuration of pulleys and belts shown below will result in the fastest rotation of Spindle 2? SIMPLE MACHINES The inclined plane The wheel and axle The lever The pulley The wedge The screw Which of these represents a properly balanced system? Fulcrum: point of rotation Moment Arm: distance from fulcrum Equilibrium is achieved when: Force X moment arm is equal at both sides of the fulcrum. Which lever requires the least effort to lift the load? EFFORT = FORCE If the load is closer to the fulcrum than the effort, you need less effort to lift the load. (5B) Demonstrate wave interactions including interference, polarization, reflection, refraction, and resonance within various materials. The diagram shows waves approaching a barrier. Which pattern will be formed after the waves pass through the opening in the barrier? (5B) QUANTITIES AND UNITS 1 f T v f Quantity Symbol Unit period T s (second) frequency f Hz (Hertz) wavelength m (meters) wavespeed v m/s A guitar player is seated next to a piano. The piano player strikes an E key on the piano. The guitarist reports that this causes the E string on his guitar to vibrate. What is the name of this phenomenon? A Polarization B Resonance C Reflection D Diffraction – wave hits a barrier and returns to its origin (bounce) Refraction – bending of light due to a change in medium (bend) Resonance – the tendency of a system to vibrate when excited by its resonant frequency (react) Interference – when two or more waves combine (meet) Polarization –allows only a certain orientation of a transverse wave through (filter) Reflection When a DVD is read, laser light touches the DVD surface and is then measured at location A. What allows light to return to location A after striking the DVD surface? F Conduction G Refraction H Magnification J Reflection An empty cup was tightly covered with plastic wrap, and a few grains of salt were sprinkled on top of the plastic. When a tuning fork was struck and placed slightly above the plastic wrap, the salt began to move. Which characteristic of waves does the movement of the salt best demonstrate? A Echo formation B Diffraction C Resonance D Specular reflection (6A) Describe the law of conservation of energy What is the approximate difference in gravitational potential energy of the two shaded boxes? A 19 J B 39 J C 59 J D 79 J THE LAW OF CONSERVATION OF ENERGY states that: The sum of all energies is the same at any point in the system. GPE mgh g 9.8 m s2 (6A) QUANTITIES AND UNITS Quantity Symbol Unit mass m kg (kilogram) height h m (meter) velocity v m/s gravitational acceleration g m/s2 kinetic energy KE J (Joules) gravitational potential energy GPE J (Joules) Fuel cells powered by plankton from the seabed can be used to operate instruments that monitor ocean currents and water temperature. These fuel cells get their energy by converting — F chemical energy to electrical energy G electrical energy to mechanical energy H hydroelectric energy to geothermal energy J mechanical energy to chemical energy The temperature of the water increases by 8°C when the metal block is added. Which could cause the temperature of the water to increase by 10°C after the metal block is added? F Using 500 g of water G Using a large beaker H Adding more 20°C water J Adding heat to the metal block THE LAW OF CONSERVATION OF ENERGY also states that: Energy must be put into a system to get energy out of a system. According to the equation E = mc2, mass — F travels at the speed of light G can be transformed into energy H contains light energy J is doubled when exposed to light 6D) Investigate and compare economic and environmental impacts of using various energy sources such as rechargeable or disposable batteries and solar cells. Which of these is an advantage of producing electricity using solar power plants rather than using coal-fired power plants? A Solar power plants can operate for about 10 hours per day. B Solar power plants can produce variable amounts of energy. C Solar power plants produce fewer pollutants. D Solar power plants require continuous sunlight. Energy Sources Fossil Fuels (coal, petroleum, natural gas) Wind Power Wave/Tidal/Hydroelectric Power Biomass (methane) Hydrogen Fuel (Fuel Cells) Solar Power Geothermal Power Nuclear Power Which of these devices uses the sun’s energy directly? A Windmill B Hydroelectric dam C Nuclear power plant D Photovoltaic cell “Photovoltaic" comes from the Greek phos meaning "light", and the name of the Italian physicist Volta, are named. It means literally of light and electricity. A company has decided to market itself as environmentally friendly. If the company is going to sell calculators, the use of which energy source would produce the fewest byproducts and the least waste? F Rechargeable batteries G Solar cells H Dry-cell batteries J Tesla coils This picture shows a small section of a solar power plant. Which of these decreases the energy production at such power plants? F Cloudy skies G Ozone in the air H Hot weather J Low humidity (6B) Investigate and demonstrate the movement of heat through solids, liquids, and gases by convection, conduction and radiation. The transfer of heat by the Conduction – transmission of movement of air currents in heat through matter (solid) Earth’s atmosphere is an example of — Convection – transmission of A conduction heat through currents B convection (fluids). Warm, low density C radiation fluid rises, cool, high density D fusion fluid sinks. Radiation – emitting energy as waves or particles. (No medium required.) (6B) QUANTITIES AND UNITS Q c p m T Quantity Symbol Unit mass m kg (kilogram) specific heat cp J/kg-K (Joules per kilogram-Kelvin) change in temperature ∆T K (Kelvin) heat gained or lost Q J (Joules) In winter the air just above the top bunk of a bunk bed is warmer than the air just above the bottom bunk because warm air rises. Which of the following describes the method of heating that causes this difference in temperature? F Radiation from the room G Heat transfer through the walls H Convection currents in the room J Heat conduction through the bed Which of these is the best example of heat transfer by radiation? A A satellite is warmed by sunlight. B Butter melts on warm bread. C A ceiling fan cools a warm room. D Puddles of water cool a warm tile floor. A man who was sleeping wakes up because he hears the smoke alarm go off in his house. Before opening the bedroom door, the man feels the door to see whether it is warm. He is assuming that heat would be transferred through the door by — A conduction B convection C radiation D compression THE END