00. Centre of Mass
Rotational Motion

149699 Assertion: When you lean behind over the hind legs of the chair, the chair falls back after a certain angle.
Reason: Centre of mass lying outside the system makes the system unstable.

1 If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
3 If Assertion is correct but Reason is incorrect.
4 If both the Assertion and Reason are incorrect.
Rotational Motion

149703 Three identical uniform thin rods each of mass ' \(m\) ' and length ' \(L\) ' are arranged in the \(X Y\) plane as shown in the figure. A fourth uniform thin rod of mass ' \(3 \mathrm{~m}\) ' is placed as shown in the figure in the XY plane. The value of length of the fourth rod such that the centre of mass of all the four rods lies at the origin is

1 \(3 \mathrm{~L}\)
2 \(2 \mathrm{~L}\)
3 \(\frac{\mathrm{L}(\sqrt{2}+1)}{3}\)
4 \(\frac{\mathrm{L}(2 \sqrt{2}+1)}{2}\)
Rotational Motion

149704 The centre of mass of a system of three particles of masses \(1 \mathrm{~g}, 2 \mathrm{~g}\) and \(3 \mathrm{~g}\) is at the origin of a co-ordinate system. If a particle of mass \(4 \mathrm{~g}\) and having position vector \(\alpha(\hat{i}+2 \hat{j}+3 \hat{k})\) is added to the three particle system, then the centre of mass of the four-particle system becomes \((1,2,3)\). The value of ' \(\alpha\) ' is

1 \(\frac{10}{3}\)
2 \(\frac{5}{2}\)
3 \(\frac{1}{2}\)
4 \(\frac{2}{5}\)
Rotational Motion

149708 Two balls are thrown simultaneously in air. The acceleration of the centre of mass of the two balls when in air :

1 is equal to \(g\) (acceleration due to gravity)
2 depends on the speeds of the two balls
3 depends on the masses of the two balls
4 depends on the direction of motion of the two balls
Rotational Motion

149699 Assertion: When you lean behind over the hind legs of the chair, the chair falls back after a certain angle.
Reason: Centre of mass lying outside the system makes the system unstable.

1 If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
3 If Assertion is correct but Reason is incorrect.
4 If both the Assertion and Reason are incorrect.
Rotational Motion

149703 Three identical uniform thin rods each of mass ' \(m\) ' and length ' \(L\) ' are arranged in the \(X Y\) plane as shown in the figure. A fourth uniform thin rod of mass ' \(3 \mathrm{~m}\) ' is placed as shown in the figure in the XY plane. The value of length of the fourth rod such that the centre of mass of all the four rods lies at the origin is

1 \(3 \mathrm{~L}\)
2 \(2 \mathrm{~L}\)
3 \(\frac{\mathrm{L}(\sqrt{2}+1)}{3}\)
4 \(\frac{\mathrm{L}(2 \sqrt{2}+1)}{2}\)
Rotational Motion

149704 The centre of mass of a system of three particles of masses \(1 \mathrm{~g}, 2 \mathrm{~g}\) and \(3 \mathrm{~g}\) is at the origin of a co-ordinate system. If a particle of mass \(4 \mathrm{~g}\) and having position vector \(\alpha(\hat{i}+2 \hat{j}+3 \hat{k})\) is added to the three particle system, then the centre of mass of the four-particle system becomes \((1,2,3)\). The value of ' \(\alpha\) ' is

1 \(\frac{10}{3}\)
2 \(\frac{5}{2}\)
3 \(\frac{1}{2}\)
4 \(\frac{2}{5}\)
Rotational Motion

149708 Two balls are thrown simultaneously in air. The acceleration of the centre of mass of the two balls when in air :

1 is equal to \(g\) (acceleration due to gravity)
2 depends on the speeds of the two balls
3 depends on the masses of the two balls
4 depends on the direction of motion of the two balls
Rotational Motion

149699 Assertion: When you lean behind over the hind legs of the chair, the chair falls back after a certain angle.
Reason: Centre of mass lying outside the system makes the system unstable.

1 If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
3 If Assertion is correct but Reason is incorrect.
4 If both the Assertion and Reason are incorrect.
Rotational Motion

149703 Three identical uniform thin rods each of mass ' \(m\) ' and length ' \(L\) ' are arranged in the \(X Y\) plane as shown in the figure. A fourth uniform thin rod of mass ' \(3 \mathrm{~m}\) ' is placed as shown in the figure in the XY plane. The value of length of the fourth rod such that the centre of mass of all the four rods lies at the origin is

1 \(3 \mathrm{~L}\)
2 \(2 \mathrm{~L}\)
3 \(\frac{\mathrm{L}(\sqrt{2}+1)}{3}\)
4 \(\frac{\mathrm{L}(2 \sqrt{2}+1)}{2}\)
Rotational Motion

149704 The centre of mass of a system of three particles of masses \(1 \mathrm{~g}, 2 \mathrm{~g}\) and \(3 \mathrm{~g}\) is at the origin of a co-ordinate system. If a particle of mass \(4 \mathrm{~g}\) and having position vector \(\alpha(\hat{i}+2 \hat{j}+3 \hat{k})\) is added to the three particle system, then the centre of mass of the four-particle system becomes \((1,2,3)\). The value of ' \(\alpha\) ' is

1 \(\frac{10}{3}\)
2 \(\frac{5}{2}\)
3 \(\frac{1}{2}\)
4 \(\frac{2}{5}\)
Rotational Motion

149708 Two balls are thrown simultaneously in air. The acceleration of the centre of mass of the two balls when in air :

1 is equal to \(g\) (acceleration due to gravity)
2 depends on the speeds of the two balls
3 depends on the masses of the two balls
4 depends on the direction of motion of the two balls
Rotational Motion

149699 Assertion: When you lean behind over the hind legs of the chair, the chair falls back after a certain angle.
Reason: Centre of mass lying outside the system makes the system unstable.

1 If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
2 If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
3 If Assertion is correct but Reason is incorrect.
4 If both the Assertion and Reason are incorrect.
Rotational Motion

149703 Three identical uniform thin rods each of mass ' \(m\) ' and length ' \(L\) ' are arranged in the \(X Y\) plane as shown in the figure. A fourth uniform thin rod of mass ' \(3 \mathrm{~m}\) ' is placed as shown in the figure in the XY plane. The value of length of the fourth rod such that the centre of mass of all the four rods lies at the origin is

1 \(3 \mathrm{~L}\)
2 \(2 \mathrm{~L}\)
3 \(\frac{\mathrm{L}(\sqrt{2}+1)}{3}\)
4 \(\frac{\mathrm{L}(2 \sqrt{2}+1)}{2}\)
Rotational Motion

149704 The centre of mass of a system of three particles of masses \(1 \mathrm{~g}, 2 \mathrm{~g}\) and \(3 \mathrm{~g}\) is at the origin of a co-ordinate system. If a particle of mass \(4 \mathrm{~g}\) and having position vector \(\alpha(\hat{i}+2 \hat{j}+3 \hat{k})\) is added to the three particle system, then the centre of mass of the four-particle system becomes \((1,2,3)\). The value of ' \(\alpha\) ' is

1 \(\frac{10}{3}\)
2 \(\frac{5}{2}\)
3 \(\frac{1}{2}\)
4 \(\frac{2}{5}\)
Rotational Motion

149708 Two balls are thrown simultaneously in air. The acceleration of the centre of mass of the two balls when in air :

1 is equal to \(g\) (acceleration due to gravity)
2 depends on the speeds of the two balls
3 depends on the masses of the two balls
4 depends on the direction of motion of the two balls