Kite or aeroplane moving horizontally: rate of change of its distance

This type of question, asked 2 times: 10 May 2024 S1, 20 Apr 2026 S2. All 2 questions below, oldest first.

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Question 1
10 May 2024 S1
128 $A kite is 120 m high and 130 m of string is out. If the kite is moving away horizontally at the rate of 39 m/sec, then the rate at which the string is being let out is$
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Question 2
20 Apr 2026 S2
75 $An aeroplane at an altitude of 1 km is flying horizontally at 600 km / hr, passes directly over an observer. Then the rate at which it is approaching the observer when it is 1250 meters away from him is........$
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Question 1