3
Select the correct answer.
How does the law of conservation of energy apply to machines?
A.
Machines create energy from scratch.
B.
Machines consume energy until no energy remains.
C.
Energy transferred to a machine equals energy transferred from it.
D.
Engineers break the law of conservation of energy by using machines.

It's because 3 if it was 10 it wouldn't look right do it goes up to 4d

Initial velocity,  u = 4.9 m/sfinal velocity = v m/sinitial height,  h₁ =  245 m    final height, h₂ = 0a = -9.8  m/s²time taken = t secondss = ut + 0.5at²⇒  (h₂-h₁) = ut + 0.5at²⇒  0-245 = 4.9t + 0.5×(-9.8)×t²⇒ -245 = 4.9t - 4.9t²⇒ 4.9t² -4.9t -245 =0solving it, we get   t = 7.59sv  = u +  at = 4.9 -9.8×7.59 = 4.9 - 74.38 = -69.48 m/svelocity is  69.48 m/s downward

Ithink the answer would be a 

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