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Work, Energy, and Power — Physics STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 SciencePhysicsWork, Energy, and Power1 Mark
Question
An elevator can carry a maximum load of $1800 kg$ (elevator + passengers) is moving up with a constant speed of $2 m s ^{-1}$. The frictional force opposing the motion is $4000 N$. Determine the minimum power delivered by the motor to the elevator in watts as well as in horse power.
✓

Answer

The downward force on the elevator is
$
F=m g+F_f=(1800 \times 10)+4000=22000 N
$
The motor must supply enough power to balance this force. Hence,
$
P= F . v =22000 \times 2=44000 W =59 hp
$

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