A helicopter of mass 3 x 10^3 kg rises vertically with constant speed of 25 m/s. What acts on the helicopter.
Correct answer: C. 3 x 10^4 N upward
- A. Zero
- B. 3 x 10^6 N downward
- C. 3 x 10^4 N upward
- D. 7.5 x 10^4 N
Explanation
The correct answer is 3 x 104 N upward. Since the helicopter is moving at a constant speed, the net force acting on it must be zero. This means the upward force exerted by the helicopter's rotors must balance the downward gravitational force. The gravitational force can be calculated as mass times gravitational acceleration (3 x 103 kg * 9.8 m/s2), which is approximately 3 x 104 N. Hence, the upward force is also 3 x 104 N to maintain the constant speed. The other options either miscalculate the gravitational force or incorrectly suggest the presence of no net force.
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