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9 grade science> an object projected vertically up from to...

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an object projected vertically up from top of a tower took 5 seconds to reach the ground. if the average velocity of the object is 5 metre per second, find its average speed. given gravity is equal to 10 metre per second.

Udbhav gupta , 6 Years ago

Grade 9

1 Answers

Eshan

Last Activity: 6 Years ago

Let the height of tower be $h$ and velocity with which ball is thrown up be $v$ .

Equation of motion for the ball’s total flight-

$-h=ut+gt^2/2 \implies -h=5u-5t^2$

Also the average velocity is given by $\dfrac{h}{t}=5m/s\implies h=25m$
Solving the two equations gives h=25m, u=20m/s

Maximum height attained by ball from the top of tower= $\dfrac{u^2}{2g}=20m$
Hence the average speed attained= $\dfrac{20m+20m+25m}{5}m/s=13 m/s$

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