A fireworks rocket is launched vertically (+y-direction) into the night sky with
ID: 1973198 • Letter: A
Question
A fireworks rocket is launched vertically (+y-direction) into the night sky with an initial speed of 44.3 m/s. The rocket coasts after being launched, then explodes and breaks into two pieces of equal mass 2.41 s later.(a) If each piece follows a trajectory that is initially at 45.6° to the vertical, what was their speed immediately after the explosion?
m/s
(b) What is the velocity of the rocket's center of mass before and after the explosion?
( m/s) y-direction
(c) What is the acceleration of the rocket's center of mass before and after the explosion?
( m/s2) y-direction
Explanation / Answer
initial velocity= 44.3 m/s
final velocity (V at t=2.41sec)= 44.3-9.8*2.41 (from v=u-at)
= 20.682 m/s in upward direction
(a) since two pices are divided in equal parts so their wight will be m/2. and their direction are at 45.6° so their speed will be same.
since no external force is working at the moment of exposion so net momentum will conserve, hence
momeentum in horizontal direction
(m/2)*v1*sin(45.6°)= (m/2)*v2*sin(45.6°)
so v1=v2
hence, momentum in vertical direction
m.20.682={2*v*m/2}cos(45.6)
v= 29.56m/s at 45.6° to the vertical
(B) since no external force is applied for expolsion so momentum will conserve.
before explosion v=20.682m/s in vertically upward direction
as mass loss is zero velocity of center of mass will be remain same as before = 20.682m/s in vertically upward direction.
(C) since no external force is working change in acceleration of center of mass will be zero.
initial acceleration= 9.8m/s^2 in vertically downdord direction
so final acceleration= 9.8m/s^2 in vertically downdord direction.
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