The angular speed of an engine wheel making 90 rev/min is _________.

(A) 1.5 π rad/s

(B)3 π rad/s

(C)4.5 π rad/s

(D)6 π rad/s

Question-3

A ring of mass m and radius r rotates about an axis passing through its center and perpendicular to its plane with angular velocity on its kinetic energy is _______

(A)

^{1}/_{2} mr^{2} ω^{2}

(B)

mrω^{2}

(C)mr^{2}ω^{2}

(D)

^{1}/_{2} mrω^{2}

Question-4

O is the centre of an equilateral triangle ABC. F_{1}, F_{2} and F_{3} are three forces acting along the side AB, BC and AC as shown in figure. What should be the magnitude of F_{3}. So that the total torque about O is zero ?

(A)

^{( F1 + F2 )} /_{2}

(B)

( F_{1} - F_{2} )

(C)

(F_{1} + F_{2} )

(D)

2 (F_{1} + F_{2} )

Question-5

If a flywheel makes 120 rev/min, then its angular speed will be

(A) 8 π rad/s

(B)6 π rad/s

(C)4 π rad/s

(D)2 π rad/s

Question-6

A ball of mass 0.25 kg attached to the end of a string of length 1.96 m is moving in a horizontal circle. The string will break if the tension is more than 25 N. What is the maximum speed with which the ball can be moved ?

(A) 14 m/s

(B)3 m/s

(C)3.92 m/s

(D)5 m/s

Question-7

A circular disc is to be made using iron and aluminium. To keep its moment of inertia maximum about a geometrical axis, it should be so prepared that

(A) Aluminium is at the interior and iron surrounds it.

(B)Iron is at the interior and aluminium surrounds it.

(C)Aluminium and iron layers are in alternate order.

(D)Sheet of iron is used at both external surfaces and aluminium sheet as inner material.

Question-8

A thin circular ring of mass M and radius r is rotating about its axis with a constant angular velocity ω. Two objects each of mass m are attached gently to the opposite ends of diameter of the ring. They will now rotate with an angular velocity.

(A)

(B)

(C)

(D)

Question-9

The moment of inertia of a disc of mass M and radius R about a tangent to its rim in its plane is

(A)^{2}/_{3} MR^{2}

(B)^{3}/_{2} MR^{2}

(C)^{4}/_{5} MR^{2}

(D)^{5}/_{4} MR^{2}

Question-10

Two bodies of mass 1 kg and 3 kg have position vectors respectively. The centre of mass of this system has a position vector

(A)

(B)

(C)

(D)

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