Mechanical Efficiency (ME) is the amount of useful work (W) a machine does.You can find the Mechanical Efficiency of a machine by dividing the Work Output (WO) by the Work Input (WI).Work output is the useful work done by a machine or work done if there was no machine. Work Input is the total work done by a machine. WO and WI can be found by multipling the force (Newtons) and the distance (metres) traveled. The force can be found by finding the mass of the object then multiplying it by 9.8, the force of gravity.The Formula used is (F x d). Work input and Work output are measured in Joules (J).
Examples: A boulder that weighs 700N is pushed up a ramp that is 9m long and 3m in height. A person uses 425 N to push the rock up the ramp.What is the efficiency of this machine?
Wout=F x d
Wout=700N x 3m
Wout=2100J
Win= F x d
Win= 425N x 9m
Win= 3375J ME=Wout/Win x 100%
ME=2100J/3375J x 100%
ME=62.2%
The Efficiency of this ramp is 62%
A box weighs 25 N while lifted through 2m. the same box requires 15N of force while pushed on a ramp 5m long. How much energy is wasted (EW) due to friction?
Wout= Fx d
Wout=25N x 2m
Wout= 50J
Win= F x d
Win= 15N x 5
Win= 75J
EW= Win-Wout
EW= 75J - 50J
EW= 25J
The amount of energy is wasted is 25J
Every machine has a mechanical efficiency less than 100% because some of the energy used is to over come the force of friction. For example, if you put water or an oil on a ramp it will increase the machines efficiency because there will be less friction between the load and the machine. Some machines cannot increase their efficiency because the surfaces in them do not rub together.
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Mechanical Efficiency (ME) is the amount of useful work (W) a machine does.You can find the Mechanical Efficiency of a machine by dividing the Work Output (WO) by the Work Input (WI).Work output is the useful work done by a machine or work done if there was no machine. Work Input is the total work done by a machine. WO and WI can be found by multipling the force (Newtons) and the distance (metres) traveled. The force can be found by finding the mass of the object then multiplying it by 9.8, the force of gravity.The Formula used is (F x d). Work input and Work output are measured in Joules (J).
Examples: A boulder that weighs 700N is pushed up a ramp that is 9m long and 3m in height. A person uses 425 N to push the rock up the ramp.What is the efficiency of this machine?
Wout=F x d
Wout=700N x 3m
Wout=2100J
Win= F x d
Win= 425N x 9m
Win= 3375J
ME=Wout/Win x 100%
ME=2100J/3375J x 100%
ME=62.2%
The Efficiency of this ramp is 62%
A box weighs 25 N while lifted through 2m. the same box requires 15N of force while pushed on a ramp 5m long. How much energy is wasted (EW) due to friction?
Wout= Fx d
Wout=25N x 2m
Wout= 50J
Win= F x d
Win= 15N x 5
Win= 75J
EW= Win-Wout
EW= 75J - 50J
EW= 25J
The amount of energy is wasted is 25J
Every machine has a mechanical efficiency less than 100% because some of the energy used is to over come the force of friction. For example, if you put water or an oil on a ramp it will increase the machines efficiency because there will be less friction between the load and the machine. Some machines cannot increase their efficiency because the surfaces in them do not rub together.
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| What is Mechanical Efficiency | Practice Test | Practice Test Answers | Bibliography |