Two bodies of mass 1 kg and 3 kg have position vectors i+2 j+ k and -3 i-2 j+ k respectively. The magnitude of position vector of centre of mass of…
JEE Main 2022 — Physics Mechanics
2022mcqeasy
Two bodies of mass 1kg and 3kg have position vectors i^+2j^+k^ and −3i^−2j^+k^ respectively. The magnitude of position vector of centre of mass of this system will be similar to the magnitude of vector :
Official previous-year question
Held on 29 Jul 2022 · Verified 6 Jul 2026.
Options
A
i^−2j^+k^
B
−3i^−2j^+k^
C
−2i^+2k^
D
−2i^−j^+2k^
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Solution
As we know, centre of mass is given by, rcom=∑mi∑miri
rcom=m+3mm(ı^+2ȷ^+k^)+3m(−3ı^−2ȷ^+k^)
rcom=4m−8mı^−4mȷ^+4mk^=−2ı^−ȷ^+k^
The magnitude of the position vector of the centre of mass is 22+11+12=6.
It is similar to the magnitude of the option A.
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