Question
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 this system will be similar to the magnitude of vector :
BITSAT
Physics
Center of Mass Momentum and Collision
2024
BITSAT 2024 (Memory Based Paper 2)
BITSAT Physics Question (2024) — Solution
Options
- A. i -2 j + k
- B. -3 i -2 j + k
- C. -2 i +2 k
- D. -2 i - j +2 k
Answer
A. i -2 j + k
Step-by-step solution
Position of COM of a mass - system is given as, r _ com = m_1 r _1+m_2 r _2 m_1+m_2 = 1( i +2 j + k )+3(-3 i -2 j + k 1+3 =-2 i - j + k | r _ c m |=|-2 i - j + k |= (2)^2+(1)^2+(1)^2 = 6 Only option (1) magnitude is 1^2+(-2)^2+1^2 = 6 So option (1) is correct.
Related: Physics — Center of Mass Momentum and Collision · All PYQ Banks