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Centre Of Mass

1. When there is no external force acts on a system of particles the velocity of centre of mass of the system.

Answer:  constant
 

2. Two objects of masses 200 g and 500 g posses velocities 10i m/s and 3i+5j m/s respectively. The velocity of their centre of mass in m/s is
Answer:  

 

3. Two identical thin uniform rods each of length L are joined to form ‘T’ shape. The distance of centre of mass of the combined system from the point of contact or joint is
Answer:   L/4

 

4. A boat of mass 300 kg and length 11m is at rest in still water. If a boy of mass 30kg walks from one end to the other, the distance through which the boat moves is (neglect the resistance of water)
Answer: 1 m

5. On a large tray of mass M an ice cube of mass m, edge L is kept. If the ice melts completely, the centre of mass of the system comes down by

Answer: 
 

6. If a uniform wire of length L is bent in the form of a semi circle, the shift in its centre of mass is
Answer:  

 

7. A ring of mass M and radius R is placed on a horizontal table. An insect of mass m is crawling along the circumference. The path of their centre of mass will be
Answer:  A Circle of radius 

8. If a square of side R/2 is removed,from a uniform circular disc of radius R as shown in the figure, the shift in centre of mass is  

Answer:  

9. Particles of masses m, 2m, 3m..., nm grams are placed on the same line at distances l, 4l, 9l, ... n2cm from a fixed point. The distance of centre of mass of the particles from the fixed point is (in cm)

Answer:  

10. Four identical bricks each of length L are arranged one above the other as shown in the figure. If the maximum distance of edge of the top most brick from the edge of the bottom brick is ‘a’ then no brick tumbles. The value of ‘a’ is  

Answer: 11L/12

11. A thin uniform rod of length L is bent at its mid point at an angle θ. The distance of centre of mass from the mid point is-
Answer 

12. The coordinates of centre of mass of letter  ‘F’ which cut from a uniform metal sheet are (Taken origin at bottom left corner)

Answer:  (15/7,33/7)

13. If the density of a thin rod of lenght L varies with the distance X from one end as        

ρ = ρo(x2/l2), the position of centre of mass of rod from one end is L
Answer: 3l/4

 

14. A uniform disc of radius of R is put over another uniform disc of radius 2 R of same thickness and density. If the peripheries of the two discs tough each other, the distance of centre of mass at the system from the centre of the larger disc toward the centre of the smaller disc is
Answer: R/5

 15. If a triangular sheet is removed from one edge of a uniform rectangular sheet as shown in the figure, then the shift in the centre of mass of the system is approsimately

 

Answer:  9cm

16. Match the following

List-I List-II
a) The centre of mass of a system doesnot depend on e) zero
b) Sum of moments of masses of a system about the centre of mass will f) constant
c) when there is no external force acts on a system its velocity of centre of mass g) uniform gravitational field
d) The centre of mass and centre of gravity coincide in h) frame of  reference

Answer: a-h, b-e, c-f, d-g

Posted Date : 15-10-2020

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గమనిక : ప్రతిభ.ఈనాడు.నెట్‌లో కనిపించే వ్యాపార ప్రకటనలు వివిధ దేశాల్లోని వ్యాపారులు, సంస్థల నుంచి వస్తాయి. మరి కొన్ని ప్రకటనలు పాఠకుల అభిరుచి మేరకు కృత్రిమ మేధస్సు సాంకేతికత సాయంతో ప్రదర్శితమవుతుంటాయి. ఆ ప్రకటనల్లోని ఉత్పత్తులను లేదా సేవలను పాఠకులు స్వయంగా విచారించుకొని, జాగ్రత్తగా పరిశీలించి కొనుక్కోవాలి లేదా వినియోగించుకోవాలి. వాటి నాణ్యత లేదా లోపాలతో ఈనాడు యాజమాన్యానికి ఎలాంటి సంబంధం లేదు. ఈ విషయంలో ఉత్తర ప్రత్యుత్తరాలకు, ఈ-మెయిల్స్ కి, ఇంకా ఇతర రూపాల్లో సమాచార మార్పిడికి తావు లేదు. ఫిర్యాదులు స్వీకరించడం కుదరదు. పాఠకులు గమనించి, సహకరించాలని మనవి.

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