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Study Guide on Work and EnergyThere will be 20 multiple choice questions and 2 free response questions. Here are some sample free response questions.Free Response Question # 1: A 6 kg concrete block is dropped from top of a tall building. The block has fallen a distance of 55 meters and has a speed of 30 meters per second when it hits the ground.At the instant the block was released, what was its gravitational potential energy with respect to the ground? (Show all calculations, including the equation and substitution with units)PE=mgh=6kg(9.8 m/s2)(55m)=3234 JCalculate the kinetic energy of the block at the point of impact. (Show all calculations, including the equation and substitution with units.)KE=1/2mv2=1/2(6kg)(30m/s)2=2700 JHow much mechanical energy was “lost” by the block as it fell?534 JUsing one or more complete sentences, explain what happened to the mechanical energy that was “lost” by the block. Heat or Thermal EnergyFree Response Question # 2:Using a metric ruler and the scale of 1 cm = 8 m, determine the height of the first hill2.5 cm= 20 mDetermine the gravitational potential energy of the car at the top of the first hill. (Show all calculations, including the equation and substitution with units.)PE=mgh=650 kg(9.8m/s2)(20 m)=127,400 JUsing one or more complete sentences, compare the kinetic energy at the top of the second hill to its kinetic energy at the top of the third hill.The kinetic energy of the car at the top of the third hill is greater than the kinetic energy at the top of the second hill.Free Response Question # 3:Name the forms of mechanical energy possessed by the system when the block is in position A and in position B.Position A:___Kinetic Energy__________ Position B:__Elastic Potential Energy___________________Free Response Question # 4:Calculate the potential energy stored in the compressed spring. (Show all work including equations and substitutions with units.) PEs=1/2kx2=1/2(150 N/m)(0.05m)2=0.1875JThe toy is activated and all the compressed spring’s potential energy is converted into gravitational potential energy. Calculate the maximum vertical height to which the toy is propelled. (Show all work including equations and substitutions with units.)PE=mgh0.1875J=(0.02 kg)(9.8m/s2)hh=0.96 mTopics to Review:Calculating work using W=FdCalculating power using P=W/t=Fd/t=FvCalculating work using the work-energy theoremAnalyzing systems in which potential energy is converted into kinetic energy using conservation of mechanical energy.Analyzing systems in which kinetic energy is converted into gravitational potential energy using conservation of mechanical energy. Such systems include pendulums, spring mass systems, rollercoasters,etc. Remember KE = ? mv2, PEg=mgh, and PEs=1/2 kx2Be able to define, explain, and calculate internal energy (work done against friction, heat) in systems. Be able to explain Hooke’s Law as it applies to elastic materials.For additional test prep, see Castle Learning. ................
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