Using relative velocity
arel=0
vrel=100
Time t for collision,
100=vrel×t
t=100100=1sec
vbullet=100−1×10=90m/s
vparticle=10×1=10m/s
S=100×1−21×10×1=95m
Pi=Pf
⇒90×0.02−10×0.03=0.05V
V=30m/s⇒h=2gv2=20900=45m
So from top of building
45−5=40m
A piece of wood of mass 0.03kg is dropped from the top of a 100m height building. At the same time, a bullet of mass 0.02kg is fired vertically upward, with a velocity 100ms−1, from the ground. The bullet gets embedded in the wood. Then the maximum height to which the combined system reaches above the top of the building before falling below is: (g=10ms−2)
Held on 10 Jan 2019 · Verified 6 Jul 2026.
40m
20m
10m
30m
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