JEE MAIN - Physics (2021 - 25th July Evening Shift - No. 7)
A balloon was moving upwards with a uniform velocity of 10 m/s. An object of finite mass is dropped from the balloon when it was at a height of 75 m from the ground level. The height of the balloon from the ground when object strikes the ground was around :
(takes the value of g as 10 m/s2)
(takes the value of g as 10 m/s2)
300 m
200 m
125 m
250 m
Explanation
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Object is projected as shown so as per motion under gravity
$$S = ut + {1 \over 2}a{t^2}$$
$$ - 75 = + 10t + {1 \over 2}( - 10){t^2} \Rightarrow t = 5$$ sec
Object takes t = 5 s to fall on ground
Height of balloon from ground
H = 75 + ut
= 75 + 10 $$\times$$ 5 = 125 m
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