# physics

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A ball is project from the building of height 250m, at angle 45degree below the horizontal with a speed of 25m/s.
i) how long does the ball remain in the air?
ii) find the magnitude and direction of the velocity of the ball just before it strikes the ground. (g=9.81m/s2)

• physics -

i) Twice the time it takes for the vertical component to become zero.
T = 2*V*sin45/g

ii) The horizontal V component remains constant at Vcos 45 and the vertical component V sin 45 changes sign, but has the same magnitude at the ground, since kinetic energy is the same there.

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