# physics

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An arrow is shot verticaaly upward. Two seconds later, it is at a height of 42 meters ( although this is not necessarily the highest point). with what speed was the arrow shot? how long is the arrow in flight altogether?

• physics -

1. h = Vo*t + 0.5g*t^2 = 42m,
Vo*2 + (-4.9)*2^2 = 42,
2Vo - 19.6 = 42,
2Vo = 42 + 19.6 = 61.6,
Vo = 30.8m/s.

2. t(up) = (Vf - Vo / g,
t(up) = (0 - 30.8) / -9.8 = 3.14s.

t(dn) = t(up) = 3.14s.

T=t(up) + t(dn) = 3.14 + 3.14 = 6.28s.=
Time in flight.

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