L> Physics Assignment answers Physics Assignment AnswersCh. 8 - EnergyCh. 8 testimonial Answers: fine kids, once dinosaurs ruled the Earth, primitive plants were busy converting light energy from sunlight intochemical potential energy (via photosynthesis) which was stored in the plants" cells. When the tree died and also were buried in sediment, they carried this potential energy with them. Time and also pressure turn these prehistoric plants (and the animals that ate them) into coal. When we burn the coal, the power we get is the energy from the sun stored by these prehistoric plants. at the really best, the amount of occupational done on an auto by the engine would certainly equal the lot of energy in the gasoline used - yet this would certainly never happen in practice. In practice, a many the power in the gasoline is lost as warm which simply heats the engine, or is lost out the tailpipe, Also, friction forces in the engine and the car takes a good deal that the energy, and a the majority of the power from the gasoline is offered for various other purposes, such as to cool the engine to keep it from melting! In practice, one "efficient" automobile powered by a petrol engine will use about 30% the the easily accessible energy for advantageous work. A machine can change an input force by an altering its (1) magnitude, or (2) direction. All devices are topic to power conservation in that no maker can output much more energy (do much more work) than the energy put right into it. Exercise is much less than or equal to Workin, or Energyout is much less than or same to Energyin. In other words, no an equipment can be more than 100% efficient. Devices cannot multiply energy or work-related input. To say the a machine has a certain mechanical benefit tells you just how much the device multiplies intake force. In various other words, if a an equipment has a mechanical benefit of 3, the an equipment will exert a force of 15 N if friend exert a pressure of 5 N. The output force is smaller than the input pressure for a kind 3 lever - the one that has the force between the fulcrum and also the load. What good could this probably be? Well, most of your bones and muscles are "wired up" as form 3 levers. Why is this? effectiveness = (workout)/(workin)(100%) = (35 J)/(100J)(100%) = 35% Theoretical mechanical benefit does not account because that friction, yes, really mechanical benefit does. If a maker were 100% reliable then it can"t have any kind of energy losses to friction, so no friction deserve to be present. In that situation the theoretical and also actual mechanical advantages would it is in equal. Effectiveness = (workout)/(workin)(100%) = (100 J)/(1000 J)(100%) = 10%Ch. 8 Plug & Chug Answers: The load of the fill is the calculation force, Fout, the this simple machine. We recognize the entry force, Fin = 50 N and the intake distance, xin = 1.2 m. The calculation distance, xout = 0.2 m exercise = workin, for this reason (Fout)(xout) = (Fin)(xin) (Fout) (0.2 m) = (50 N)(1.2 m) Fout = 300 N (a) practice = workin, therefore (Fout)(xout) = (Fin)(xin) (5000 N) (0.4 m) = (Fin)(2 m) Fin = 1000 N (b) efficiency = (workout)/(workin)(100%) practice = (5000 N)(0.4 m) = 2000 J workin = (2500 N)(2 m) = 5000 J, so, performance = (2000 J)/(5000 J)(100%) = 40 %
I"m impressed. Ch. 8 Think & describe Answers: (a) (left-hand diagram) Mechanical benefit = 1, due to the fact that the force-to-fulcrum distance equates to the load-to-fulcrum distance. (b) (middle diagram) Mechanical benefit = 2, since the force-to-fulcrum distance is double the load-to-fulcrum distance. (c) (b) (right-hand diagram) Mechanical benefit = 0.5, due to the fact that the force-to-fulcrum street is fifty percent the load-to-fulcrum distance. The power released by a atom reactor is atom potential energy, or mass (E = mc2). Energy is conserved in a atom reactor. Ch. 8 Think & settle Answers: Ok, a liter that gasoline has 40 MJ (mega-joules) that energy. If the engine is 25% efficient, the engine will produce (0.25)(40 MJ) = 10 MJ of helpful work. If that appears a little bit "slick", below are the details:
This 10 MJ of energy can do work to actually relocate the car. The engine will need to generate a force of 1000 N to relocate the vehicle at constant velocity. Since W = Fd,(10 MJ) = (1000 N)(d)d = 10 000 m = 104 m = 10 km. The mechanical benefit of the pulley system on the best is 2. I really don"t prefer to take into consideration pulleys to be levers, but notice that there space 2 ropes lifing the object.

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Therefore, the stress and anxiety in each rope equals fifty percent the load of the object. You have to use a pressure of 0.5W come lift a load W, so the mechanical benefit is: MA = (Forcewithout)(Forcewith) = 2