Adyar – Adambakkam – Pallavaram – Pammal – Chromepet – East Tambaram
Std:- XI
Dynamics of rotational motion
Sub:- Physics
I.
Choose the correct answer:1.
The angular speed of minute arm in a watch is ________ rad.s-1.
a) π/1800
2.
3.
b) π/3600
d) π/21600
a) The angular velocity
b) The mass
c) The axis of rotation
d) The distribution of mass
Rotational analogue of mass in linear motion is
b) moment of inertia
c) Weight
d) angular momentum
The rate of change of angular momentum is equal to
a) Torque
5.
c) π/12
The moment of inertia of a body does not depend on ________ of the body.
a) Torque
4.
Marks:- 75
Time:- 1.30 min
14 X 1 = 14
b) Force
c) moment of inertia
d) angular acceleration.
A man is sitting on a rotating stool with his arms outstretched, suddenly he folds his
arms. The angular velocity
a) Becomes zero
6.
8.
b) torque
c) angular acceleration
d) moment of inertia
a) Always
b) in the absence of external torque
c) in the presence of external torque
d) never
The moment of inertia of a body comes into play in
c) periodic motion
c) rotational motion
d) linear motion
The unit of couple is
a) N
10.
d) decreases
Angular momentum of the body is conserved
a) Projectile motion
9.
c) increases
The rate of change of angular velocity is equal to
a) Force
7.
b) remains constant
b) Nm
The dimension of radius of gyration is
c) Nm-1
d) Nm-2
a) MLT-1
11.
b) ML2T-1
b) minimum
c) zero
d) finite
c) 90˚
d) 180˚
The torque is maximum when θ =
a) 0˚
13.
d) M-1L-1T-2
The stable equilibrium, the potential energy is
a) Maximum
12.
c) L
b) 45˚
Starting from rest, the flywheel of a motor attains an angular velocity 100 rad/s in 10 s.
The angular acceleration is
a) 0 rad.s-2
14.
b) 100 rad.s-2
c) 10 rad.s-2
d) none of these
The moment of inertia of a disc about an axis passing through its center and
perpendicular to its plane is
a) ½ MR2
b) MR2
c) ¼ MR2
d) 5/4 MR2
II.
Answer in brief:-
7 x 3 = 21
15.
What are the different types of equilibrium?
16.
State parallel axes theorem.
17.
State the law of conservation of angular momentum.
18.
Compute the rotational kinetic energy of a 2 Kg wheel rotating at t revolutions per second
if the radius of gyration of the wheel is 0.22 m.
19.
Give two examples for conservation of angular momentum.
20.
Write the equations of rotational motion.
21.
Define centre of gravity.
22.
What is the physical significance of moment of inertia?
III.
Answer in a paragraph:-
23.
State and prove perpendicular axes theorem.
24.
Compare linear motion with rotational motion.
25.
A solid sphere of 50 g and diameter 2 cm rolls without sliding with a uniform velocity of
4 x 5 = 20
5 ms-1 along a straight line on a smooth horizontal table. Calculate its total kinetic energy.
26.
Derive the relation between torque and angular acceleration.
IV.
Answer in detail:-
27.
Obtain an expression for position of centre of mass of two particle system.
28.
Derive the relation between rotational kinetic energy and moment of inertia of a rigid
body.
2 x 10 =20