please help me in my physics assignment...?

a baseball thrown at an angle of 60degrees above the horizontal strikes a building 18m away at a point 8m above the point from which it is thrown. ignore air resistance.

a.) find the magnitude of the initial velocity of the baseball

b.) find the magnitude & direction of the velocity of the baseball just before it strikes the building.

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  • 1 decade ago
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    a)

    Let the initial velocity be called, v.

    x-component: v_x=vcos60

    y-component: v_y=vsin60

    t=x/v_x

    t=18/vcos60=36/v

    ∆y=v_y*t-1/2 at^2

    8=vsin60(36/v)-1/2 (9.8)(36/v)^2

    8=36sin60-6350/v^2

    23.2=6350/v^2

    v=16.5m/s

    b) v_x=16.5cos60=8.25m/s

    t=36/v=2.18s

    v_y=v_o+at

    v_y=36sin60-9.8(2.18s)

    v_y=9.81m/s

    √(v_y^2+v_x^2)=magnitude= 12.8m/s

    tan^-1(9.81/8.25)=θ=49.9deg

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