(a) 147,500 J
Newton's second law, applied to the helicopter, states that
where
F is the lifting force
mg is the weight of the helicopter, with m=500 kg being the mass of the helicopter and g=9.8 m/s^2 the acceleration due to gravity
a=2.00 m/s^2 is the acceleration of the helicopter
From the equation, we can calculate the magnitude of the lifting force:
The vertical distance covered by the helicopter is given by
So, the work done by the lifting force F is
2) -122,500 J
The magnitude of the gravitational force acting on the helicopter is
And the work done by this force on the helicopter is
And the negative sign is due to the fact that the direction of the gravitational force is opposite to the displacement of the helicopter.
3) 25,500 J
The net work done on the helicopter is given by the sum of the work done by the two forces:
X=92.49 m
Explanation:
Given that
u= 21 m/s
h= 97 m
Time taken to cover vertical distance h
h= 1/2 g t²
By putting the values
97 = 1/2 x 10 x t² ( g = 10 m/s²)
t= 4.4 s
The horizontal distance
X= u .t
X= 21 x 4.4
X=92.49 m