KinematicsMedium
Question
A paratrooper jumps from an aeroplane and opens a parachute after 2 s of free fall and starts deaccelerating with $3\text{ }m/s^{2}$. At 10 m height from ground, while descending with the help of parachute, the speed of paratrooper is $5\text{ }m/s$. The initial height of the aeroplane is $\_\_\_\_$ m.
$$\left( g = 10\text{ }m/s^{2} \right) $$
Options
A.62.5
B.92.5
C.20
D.82.5
Solution
A to B
$${x_{1} = \frac{1}{2} \times 10 \times 2^{2} = 20\text{ }m }{V = 0 + 10 \times 2 }$$B to C
$${5^{2} = 20^{2} - 2(3)x_{2} }{x_{2} = \frac{375}{6} }{x_{2} = 62.5 }$$C to D
$${x_{3} = 10\text{ }m }{H = x_{1} + x_{2} + x_{3} = 92.5 }$$
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