A crane lifts a 1400kg girder 96m in 2.5 minutes.
1. How much useful work does the crane do?
2. What is the increase in potential energy of the girder?
3. What is the useful power of the crane?
4. The crane motor is rated at 28kW is its efficiency?
5. Give at least 2 reasons why efficiency is less than 100%
1. How much useful work does the crane do?
2. What is the increase in potential energy of the girder?
3. What is the useful power of the crane?
4. The crane motor is rated at 28kW is its efficiency?
5. Give at least 2 reasons why efficiency is less than 100%
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1) F.s = 1400 g * 96
2) mgh= 1400*g* 96
3) power=w/t= 1400*g*96/2.5 min=8.960kW
4) efficiency= [8.960/28] *100
5) a] energy is lost in friction between the chains of crane which r used to lift the grider
b] damping in air or u can say air resistance
2) mgh= 1400*g* 96
3) power=w/t= 1400*g*96/2.5 min=8.960kW
4) efficiency= [8.960/28] *100
5) a] energy is lost in friction between the chains of crane which r used to lift the grider
b] damping in air or u can say air resistance