A boy sees a ball going up and then back down through a window $$2.45$$ m high. If the total time taken by the ball is $$1$$ $$sec$$, the height above the window that the ball rises is

Question

Infinity Learn · Accepted Answer

Here the ball is in sight for $$1$$ $$sec$$. Thus the ball takes $$1/2$$ second to go up across the window and $$1/2$$ second to come down across it. Let h be the height that the ball rises above the window and t be the time taken to fall through h. Then the time taken to fall through the $$distance(h+2$$⋅$$45)m$$ would be $$t+12$$ $$henceh=0$$×$$t+12gt2$$ or $$h=12gt2$$....(1)and$$ $$(h+2$$⋅$$45)=0$$×$$t+12+12gt+122$$....$$(2)From$$ eqs. $$(1) and $$(2)12gt2+2$$⋅$$45=12gt+122Solving$$, this equation, we $$gett=14sec$$∴ $$h=12$$×$$9$$⋅$$8$$×$$142=0$$⋅$$306m$$

A boy sees a ball going up and then back down through a window 2.45 m high. If the total time taken by the ball is 1 sec, the height above the window that the ball rises is

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