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physics

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a ball rolls down a roof that makes an angle of 30 to horizontal.it rolls off the egde with a speed of 5.00m/s.distance to the ground from that point is 7.00m
a)how long is the ball in the air
b)how far from the base of the house does it land?
c)what is its speed just before landing?

  • physics - ,

    v(ox) = v•cosα =5•cos30 = 4.33 m/s,
    v(x) = v(ox) = 4.33 m/s,
    v(oy) = v•sinα =5•sin30 = 2.5m/s.
    h =v(oy) •t+g•t^2/2,
    4.9•t^2 +2.5•t-7 =0
    t = 1.05 s.
    L =v(ox) •t = 4.33•1.05 = 4.55 m
    v(y) = v(oy) + g•t = 2.5 +9.8•1.05 = 12.8 m/s,
    v=sqrt{v(x)^2 + v(y)^2} = 13.5 m/s.

  • physics - ,

    quadratic equation is solved incorrectly 4.9•t^2 +2.5•t-7 =0
    t IS NOT = 1.05 s , it is 0,967047 seconds.
    then put this time to solve other stuff

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