Proj Motion EX 10

Helena Dedic

A ball rolls of a 1 m-high table and lands 1.6 m along the floor. Find its initial speed and the time of flight.

Solution:

The ball rolls along the table with horizontal velocity. When the ball leaves the table, the initial velocity is horizontal so that$v_{xo}=v_o$ and $v_{yo}=0$. We know that $\mathrm{\Delta }x$ = 1.6 m and $\mathrm{\Delta }y$ = -1.0 m. We can write:

Eq. 1	$\mathrm{\Delta }x=v_{xo}t$	$1.6m=v_{xo}t$	(a)
Eq. 2	$\mathrm{\Delta }y=0-4.9t^2$	$-1.0=0-4.9t^2$	(b)

Solve equations (a) and (b) for initial velocity, $v_{xo}=v_o$, and time of flight, t.

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