COM of Continuous Bodies — NEET Physics MCQs with Solutions
Free NEET Physics COM of Continuous Bodies MCQs with step-by-step solutions (8 questions). Part of Centre of Mass, Momentum & Collisions. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — COM of Continuous Bodies · easy · theory
The centre of mass of a uniform semicircular RING of radius R lies on the symmetry axis at a distance from the centre of:
A. 2R/π ✓ Correct
B. 4R/3π
C. R/2
D. R/π
Solution: Standard results: semicircular ring 2R/π; semicircular DISC 4R/3π — don't swap them.
Q2 — COM of Continuous Bodies · medium · theory
The COM of a uniform solid HEMISPHERE of radius R lies above the flat face at:
A. 3R/8 ✓ Correct
B. R/2
C. 2R/π
D. 3R/5
Solution: Solid hemisphere: 3R/8. (Hollow hemispherical shell: R/2; solid cone: h/4 above the base.)
Q3 — COM of Continuous Bodies · easy · numerical
A uniform rod of length 2 m has its centre of mass at a distance from one end of:
A. 0.5 m
B. 1 m ✓ Correct
C. 2/3 m
D. 1.5 m
Solution: A uniform rod's COM is at its midpoint: L/2 = 1 m.
Q4 — COM of Continuous Bodies · medium · numerical
A rod of length 1 m has linear density λ = 2x (kg/m). The COM from the light end (x = 0) is at:
A. 1/3 m
B. 3/4 m
C. 2/3 m ✓ Correct
D. 1/2 m
Solution: x_cm = ∫xλdx/∫λdx = (∫2x²)/(∫2x) = (2/3)/(1) = 2/3 m — shifted towards the heavy end.
Q5 — COM of Continuous Bodies · hard · numerical
A uniform solid CONE of height 12 cm stands on its base. Its centre of mass is above the base at:
A. 8 cm
B. 4 cm
C. 3 cm ✓ Correct
D. 6 cm
Solution: COM of a solid cone is h/4 above the base = 3 cm (or 3h/4 below the apex).
Q6 — COM of Continuous Bodies · medium · numerical
A uniform semicircular disc has radius 21 cm (π ≈ 22/7). Its COM lies above the centre at 4R/3π =
A. ≈ 13.4 cm
B. ≈ 6.7 cm
C. ≈ 10.5 cm
D. ≈ 8.9 cm ✓ Correct
Solution: 4R/3π = 4×21/(3×22/7) = 84×7/66 ≈ 8.9 cm.
Q7 — COM of Continuous Bodies · easy · numerical
The centre of mass of a uniform circular RING lies:
A. At its geometric centre, where there is no mass ✓ Correct
B. On the rim
C. R/2 above the centre
D. At 2R/π from the centre
Solution: By symmetry the COM is the centre — an empty point, showing the COM need not lie within the material.
Q8 — COM of Continuous Bodies · medium · numerical
An L-shaped lamina is made of two identical uniform squares of side 1 m — one at the origin, one directly to its right. The COM of the combination is at:
A. (1, 1) m
B. (1, 0.5) m ✓ Correct
C. (0.5, 0.5) m
D. (0.75, 0.5) m
Solution: Centres: (0.5, 0.5) and (1.5, 0.5), equal masses ⇒ midpoint (1, 0.5).