worker throws wrench downward form a height of 128feet withinitial velocity of 3

Question

worker throws wrench downward form a height of 128feet withinitial velocity of 32 feet per second. The height of wrench abovethe ground after t seconds is given by S(t)=-16t-32t+128 a: what is the height of the wrench after 1 second? b: How long does it take for the wrench to reach theground? worker throws wrench downward form a height of 128feet withinitial velocity of 32 feet per second. The height of wrench abovethe ground after t seconds is given by S(t)=-16t-32t+128 a: what is the height of the wrench after 1 second? b: How long does it take for the wrench to reach theground?

Explanation / Answer

S(t) = - 16t^2 - 32t + 128    , I take it thatit should be - 16t^2 and not - 16t a) S(1) = -16(1)^2 - 32(1) + 128 = - 48 + 128 = 80 so the wrench is at 80 feet at t = 1 b) we set S(t) = 0 = - 16t^2 - 32t + 128 so    t^2 + 2t - 8 =0      when we divide through by -16      so t = [ - 2 ±[2^2 - 4(1)(-8)] ] / 2 = [ - 2 ± 36 ] / 2 = [- 2 ± 6 ] / 2       so t = - 4 or t =2   since time cannot be negative   the wrenchhits the ground at                                     2 seconds hope this helps

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