Question

A stone falls freely from rest for 4 seconds. A) calculate the final velocity b) what distance does the stone fall during this time?

Answer 1

Hey ! Here it is;

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A)

u=0
v=?
t=4secs.
g=9.8m/s²

$v = u + gt$

v=0+9.8(4)
v=39.2m/s

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B)

v=39.2 m/s
u=0
t=4secs
g=9.8m/s²

${v}^{2} - {u}^{2} = 2gs$
(39.2)²-(0)²=2(9.8)s
1536.64-0=19.6s
1536.64/19.6=s
s=78.4 m
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Answer 2

v=? u=0 g=10m/s^2 t=4 sec
V=U+gt
V=0+10×4
V=40m/s

The final velocity of stone is 40m/s
The total distance travelled
by the stone is

$s = ut + \frac{1}{2}gt^{2}$
$s = 0 \times 4 + \frac{1}{2}10 \times 4 {}^{2}$
$s = 0 + \frac{1}{2} \times 10 \times 16 \\ s = 160 \times \frac{1}{2} \\ s = 80m$