A block moving horizontally on a smooth surface with a speed of 20m/s,bursts into two equal parts continuing in the same direction.If one of the parts moves at 30m/s,then:
-Find out how the speed of the second part is 10m/s.
-How is the fractional change in the kinetic energy 1/2.
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As we know from the conservative of momentum
m1v1 = m2v2
let mass of block is 2m and it breaks into m and m
then,
2m×20 = m×30 + m×a (a is the velocity of 2nd part)
40m = m(30 + a)
40 = 30 + a
a = 10 m/s
initial KE = 1/2×(2m)×(20)^2
= 400m
final KE = 1/2×(m)×(30)^2 + 1/2×(m)×(10)^2
= 1/2×m×(900 + 100)
= 500m
The fractional change is 1/4 not 1/2.
^_^
m1v1 = m2v2
let mass of block is 2m and it breaks into m and m
then,
2m×20 = m×30 + m×a (a is the velocity of 2nd part)
40m = m(30 + a)
40 = 30 + a
a = 10 m/s
initial KE = 1/2×(2m)×(20)^2
= 400m
final KE = 1/2×(m)×(30)^2 + 1/2×(m)×(10)^2
= 1/2×m×(900 + 100)
= 500m
The fractional change is 1/4 not 1/2.
^_^
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