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A helicopter flying horizontally with a speed of 360~km/h at an altitude of 2 km, drops an object at an instant. The object hits the ground at a point O, 20 s after it is dropped. Displacement of 'O' from the position of helicopter where the object was released is: (use acceleration due to gravity g=10~m/s^2 and neglect air resistance) [cite: 157, 158, 159, 160]

Solution & Explanation

### Related Formula x = u cdot t [cite: 763] H = frac12gt^2 [cite: 764] D = sqrtx^2 + H^2 [cite: 774] ### Core Logic First, convert the horizontal velocity component to metric SI units: [cite: 157, 763] u = 360 times frac518 = 100\ textm/s [cite: 157, 763] Calculate the horizontal range distance x covered over t = 20\ texts: [cite: 158, 763] x = 100 times 20 = 2000\ textm = 2\ textkm [cite: 158, 763] The vertical displacement height H is explicitly given as 2\ textkm = 2000\ textm[cite: 157, 769]. Let's confirm with free-fall height calculation matching the solution template: [cite: 764] H = frac12 times 10 times (20)^2 = 5 times 400 = 2000\ textm = 2\ textkm [cite: 158, 769] Now find the net spatial vector displacement D from the release coordinates: [cite: 774] D = sqrtx^2 + H^2 = sqrt2^2 + 2^2 = sqrt8 = 2sqrt2\ textkm [cite: 774] ### Pattern Recognition Be careful with the wording: the question asks for the displacement from the *release coordinate position* [cite: 159], which is the hypotenuse vector sqrtx^2 + H^2[cite: 774]. Do not mistake it for the horizontal range distance alone. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Physics: Motion in a Plane
Projectile motion diagram for Q18 - JEE Main 2025 Evening
Projectile motion diagram for Q18 - JEE Main 2025 Evening

Reference Study Guides

More Motion in a Plane Previous-Year Questions — Page 2

Q25 2025 Relative Motion
The maximum speed of a boat in still water is 27 \, textkm/h . Now this boat is moving downstream in a river flowing at 9 \, textkm/h . A man in the boat throws a ball vertically upwards with speed of 10 \, textm/s . Range of the ball as observed by an observer at rest on the river bank, is ________ cm. (Take g = 10 \, textm/s^2 ) [cite: 1, 2]
Numerical Answer. Answer: 2000 to 2000

Solution

### Related Formula T = frac2u_yg, quad R = v_x cdot T ### Core Logic
Relative range tracking frame vector
Relative range tracking frame vector
The total horizontal velocity components combine due to downstream motion addition [cite: 2, 730]: v_x = 27 + 9 = 36text km/h = 36 cdot frac518 = 10text m/s [cite: 730, 740] The time of flight for the vertical launch tracking stands at : T = frac2 cdot 1010 = 2text s Horizontal range measured along the river bank frame is : Range = v_x cdot T = 10 cdot 2 = 20text m = 2000text cm ### Chapter Mix Class 11 Physics: Motion in a Straight Line Class 11 Physics: Motion in a Plane

More Motion in a Plane Questions — jee_main_2025_07_april_evening

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