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26/01/2022 12:48 pm
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A block moving horizontally on a smooth surface with a speed of 40 ms-1 splits into two equal parts. If one of the parts moves at 60 ms-1 in the same direction, then the fractional change in the kinetic energy will be x : 4 where x =__________.
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26/01/2022 1:02 pm
Pi = Pf
m x 40 = \(\frac{m}{2}\) x v + \(\frac{m}{2}\) x 60
40 = \(\frac{v}{2}\) + 30
⇒ v = 20
(K.E)I = \(\frac{1}{2}\)m x (40)2 = 800 m
(K.E)f = \(\frac{1}{2}\)\(\frac{m}{2}\).(20)2 + \(\frac{1}{2}\).\(\frac{m}{2}\)(60)2 = 1000 m
|ΔK.E.| = |1000m - 800m| = 200 m
\(\frac{ΔK.E}{(K.E)_i}\) = \(\frac{200m}{800m}\) = \(\frac{1}{4}\)
= \(\frac{x}{4}\)
x = 1