Science 7: Today we went over the answers to that crazy crossword from yesterday. We also looked at the information needed to review for the quiz Thursday. Reminder to bring your textbook to class tomorrow as we're going to continue with our review. Pg 237 in the textbook #'s 1-4 due for tomorrow.
Science 8: Went over the information on 'Combining Systems' and then looked at information to review for Quiz tomorrow. Review Questions on pg 331, #1,3,4,5,7,8,9 to hand in tomorrrow before the quiz. Bring your textbook as we'll be doing more work after the quiz.
Review Questions done in class:
Pressure and Efficiency Calculations – Gr 8. Mechanical Systems
Two pistons, the smaller one exerting a force of 200N, each having an area of 2m2 and 8m2. What is the force of the larger piston?
F2=800N
A hydraulic lift requires you to exert a force of 50N in order to lift a load of 150N. What is the area of the load piston if the first piston has an area of 5m2?
A2=15m2
One piston has an area of 2m2, the other has an area of 6m2. If there is a force exerted on the smaller piston of 100N, what is the force on the larger piston?
F2=300N
Calculate the efficiency of a machine that produces 725J of work on a load when 800J is exerted on the machine.
Eff=90.6%
A machine is rated as 95% efficient. If the amount of work done on a load is 660J, calculate the amount of work needed to be exerted on the machine.
EW=694.7J
A pulley system exerts a total of 850J of work on a bridge. Calculate the efficiency of this pulley system if the work needed on this machine was equal to lifting the bridge deck of 200N to a height of 6m.
Eff=70.8%
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