Tiêu đề System of particles & Rotational Motion.pdf ✅

Exercise 1: NCERT Based Topic-wise MCQs 8.1 INTRODUCTION 1. In rotatory motion, linear velocities of all the particles of the body are NCERT Page-142, 143 / N-93 (a) same (b) different (c) zero (d) cannot say 2. The motion of a rigid body which is not pivoted or fixed in some way is either a pure ...A... or a combination of translation and rotation. The motion of a rigid body which is pivoted or fixed in some way is ... B... Here, A and B refer to NCERT Page-144/N-94 (a) rotation and translation (b) translation and rotation (c) translation and the combination of rotation and translation (d) None of the above 3. In rotation of a rigid body about a fixed axis, every ...A...of the body moves in a ...B..., which lies in a plane ...C... to the axis and has its centre on the axis. Here, A, B and C refer to NCERT Page-143 / N-94 (a) particle, perpendicular and circle (b) circle, particle and perpendicular (c) particle, circle and perpendicular (d) particle perpendicular and perpendicular 4. The centre of mass of a body NCERT Page-145, 146 / N-96,97 (a) lies always outside the body (b) may lie within, outside on the surface of the body (c) lies always inside the body (d) lies always on the surface of the body 5. Two bodies of mass 1 kg and 3 kg have position vectors iˆ + 2jˆ + k and −3iˆ − 2jˆ + kˆ respectively. The magnitude of position vector of centre of mass of this system will be similar to the magnitude of vector: (a) iˆ − 2jˆ + kˆ NCERT Page-145/N-96 (b) −3iˆ − 2jˆ + kˆ (c) −2iˆ + 2kˆ (d) −2iˆ − jˆ + 2kˆ 6. The position of centre of mass of a system of particles does not depend upon the NCERT Page-145 / N-96 CHAPTER SYSTEM OF PARTICLES & 8 ROTATIONAL MOTION NCERT LINE BY LINE PHYSICS - +919441258413
(a) mass of particles (b) symmetry of the body (c) position of the particles (d) relative distance between the particles 7. The mass per unit length of a non - uniform rod of length L varies as m = λx where λ is constant. The centre of mass of the rod will be at ; NCERT Page-146, N-97 (a) 2 3 L (b) 3 2 L (c) 1 2 L (d) 4 3 L 8. The motion of the centre of mass depends on NCERT Page-148/N-99 (a) total external forces (b) total internal forces (c) sum of (a) and (b) (d) None of these 9. The centre of mass of two particles lies on the line NCERT Page-145 / N-96 (a) joining the particles (b) perpendicular to the line joining the particles (c) at any angle to this line (d) None of these 10. Three identical spheres, each of mass 1 kg are kept as shown in figure, touching each other, with their centres on a straight line. If their centres are marked P, Q, R respectively, the distance of centre of mass of the system from P is NCERT Page-145 / N-96 (a) PQ+PR+QR 3 (b) PQ+PR 3 (c) PQ+QR 3 (d) PR+QR 3 11. The coordinates of centre of mass of a uniform flag shaped lamina (thin flat plale) of mass 4 kg. (The coordinates of the same are shown in figure) are: NCERT Page-145, 146/N-98 (a) (1.25 m, 1.50 m) (b) (0.75 m, 1.75 m) (c) (0.75 m, 0.75 m) (d) (1 m, 1.75 m)
12. Two spheres A and B of masses m and 2m and radii 2R and R respectively are placed in contact as shown. The COM of the system lies NCERT Page-145/N-96 (a) inside A (b) inside B (c) at the point of contact (d) None of these 13. Centre of mass of the earth and the moon system lies NCERT Page-145/N-96 (a) closer to the earth (b) closer to the moon (c) at the mid-point of line joining the earth and the moon (d) cannot be predicted 14. A stick is thrown in the air and lands on the ground at some distance from the thrower. The centre of mass of the stick will move along a parabolic path NCERT Page-145 / N-96 (a) in all cases (b) only if the stick is uniform (c) only if the stick has linear motion but no rotational motion (d) only if the stick has a shape such that its centre of mass is located at some point on it and not outside it 15. The motion of binary stars, S1 and S2 is the combination of ........ and ....Y.... . Here, X and Y refer to (a) motion of the CM and motion about the CM (b) motion about the CM and motion of one star (c) position of the CM and motion of the CM (d) motion about CM and position of one star 16. Consider a system of two particles having masses m1 and m2. If the particle of mass m1 is pushed towards the centre of mass particles through a distance d, by what distance would the particle of mass m2 move so as to keep the mass centre of particles at the original position? NCERT Page-145/N-96 (a) m2 m1 d (b) m1 m1+m2 d (c) m1 m2 d (d) d 17. Three masses are placed on the x-axis : 300 g at origin, 500 g at x = 40 cm and 400 g at x = 70 cm. The distance of the centre of mass from the origin is NCERT Page-145/N-96 (a) 40 cm (b) 45 cm
(c) 50 cm (d) 30 cm 18. A system consists of three particles, each of mass m and located at (1,1), (2,2) and (3,3). The co-ordinates of the centre of mass are NCERT Page-145/N-96 (a) (1,1) (b) (2,2) (c) (3,3) (d) (6,6) 19. Four particles of masses m1, m2, m3 and m4 are placed at the vertices A, B, C and D as respectively of a square shown. The COM of the system will lie at diagonal AC if NCERT Page-145/N-96 (a) m1 = m3 (b) m2 = m4 (c) m1 = m2 (d) m3 = m4 20. In the figure shown ABC is a uniform wire. If centre of mass of wire lies vertically below point A, then BC AB is close to NCERT Page-145 / N-96 A (a) 1.85 (b) 1.5 (c) 1.37 (d) 3 21. A circular hole of radius ( a 2 ) is cut out of a circular disc of radius ' a ' as shown in figure. The centroid of the remaining circular portion with respect to point ' O ' will be: NCERT S Page-145 / N-97 (a) 1 6 a (b) 10 11 a (c) 5 6 a (d) 2 3 a 22. The centre of mass of three bodies each of mass 1 kg located at the points (0,0), (3,0) and (0,4) in the XY plane is NCERT Page-145/N-96 (a) ( 4 3 , 1) (b) ( 1 3 , 2 3 ) (c) ( 1 2 , 1 2 ) (d) (1, 4 3 )