A helicopter of mass 2000 kg rises with a vertical acceleration of `15ms^-2`. The total mass of the crew and passengers is 500 kg. Give the magnitude and direction of the (g`=10ms^-2`)
(a) Force on the floor of the helicopter by the crew and passengers.
(b) action of the rotor of the helicopter on the surrounding air.
(c ) force on the helicopter dur to the surrounding air.

Options

A. I and ii
B. ii and iii
C. I and iii
D. All the three

Answer

D

Explanation

Here, Mass of the helicopter, M=2000kg
Mass of the crew and passengers, m=500kg
Vertically upwards acceleration, `a=15ms^(-2)`
(i) Force on the floor by the crew and passengers `m=(g+a)=500kg(10+15)ms^(-2)`
`=12500N=1.25xx10^(4)N`
It acts vertically downwards.
(ii) Action of the rotor of the helicopter on the surrounding air=(M+m) (g+a) `=(2000+500)kg (10+15)ms^(-2)`
`=62500N=6.25xx10^(4)N` It acts vertically downwards.
(iii) Force on the helicopter due to the surrounding air is equal and opposite to the action of the rotor of the helicopter on the surrounding air.
Force on the helicopter due to the surrounding air=`6.25xx10^(4)N`.
It acts vertically upwards