A parachute increases air friction, thus reducing falling speed.
Indeed, the air friction is roughly proportional to the surface of the object falling down; the parachute tremendously increases that surface.
<span>A. Boyle's law only works when the pressure is constant.
</span><span>D. Charles's law relates volume and pressure.
Hope this helps!</span>
Gravity acts to influence the vertical motion of the projectile, thus causing a vertical acceleration. The horizontal motion of the projectile is the result of the tendency of any object in motion to remain in motion at constant velocity.
Answer:
Lifting force, F = 21240 N
Explanation:
It is given that,
Mass of the helicopter, m = 1800 kg
It rises with an upward acceleration of 2 m/s². We need to find the lifting force supplied by its rotating blades. It is given by :
F = mg + ma
Where
mg is its weight
and "ma" is an additional acceleration when it is moving upwards.
So, 
F = 21240 N
So, the lifting force supplied by its rotating blades is 21240 N. Hence, this is the required solution.