A body of mass 100 kg stands on a spring weighing machine inside a lift. The lift starts to
ascend with acceleration of 2.2 m s-2. What is the reading of the machine?
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A body of mass 100 kg stands on a spring weighing machine inside a lift. The lift starts to
ascend with acceleration of 2.2 m s-2. What is the reading of the machine?
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Explanation:
Speed of wind on the upper surface of the wing, V1=70m/s
Speed of wind on the lower surface of the wing, V2=63m/s
Area of the wing, A=2.5m2
Densityof air, ρ=1.3kg/m3
According to Bernoullis theorem, we have the relation:
P1+(1/2)ρ(V12)=P2+(1/2)ρ(V22)
P2−P1=(1/2)ρ(V12−V22)
Where,
P1= Pressure on the upper surface of the wing
P2= Pressure on the lower surface of the wing
The pressure difference between the upper and lower surfaces of the wing provides lift to the aeroplane.
Lift on the wing =(P2−P1)A
=(1/2)ρ(V12−V22)A
=(1/2)1.3[702−632]2.5
=1512.87
N=1.51×103 N
Therefore, the lift on the wing of the aeroplane is 1.51×103 N.