If 7 men can do a certain job in 12 days, how long would it take 6 mens to do the same job?
1 answer:
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A projectile is an object <u>launched</u> into space, and moving under the <em>influence</em> of <u>gravity</u> and <u>momentum</u>. The <em>stone</em> here is an example. Thus, the <em>time</em> taken for the stone to reach the ground is 10 seconds.
On <em>launching</em> of the stone into <u>space</u>, it behaves as a <u>projectile</u>. Thus moving under the <em>influence</em> of gravity and its momentum. Its <u>momentum</u> is the <em>product</em> of its <u>mass </u>and <u>velocity</u>.
The height h, is given as:
h = 16 + 32t + 240
Differentiating the expression with respect to t, we have;
32t + 32 = 0
t = -1 seconds
Substitute the value of time, t, in the equation for the height;
h = 16 - 32 + 240
= 224
h = 224 m
Total height, S = 240 + 224
= 464
S = 464 m
The total height covered by the stone is 464 m.
From the second equation of <em>free fall</em>,
S = Ut + g
S = g
464 = *9.8*
=
= 94.694
t =
= 9.7311
t ≅ 10 seconds
The <em>time taken</em> for the stone to hit the ground is 10 seconds.
Thus option A is the required answer.