A thin conducting ring and radius R is given charge +Q. The electric field at the centre O of the ring due to the charge on the part AKB of the ring is E. The electric field at the centre due to the charge on the part ACDB of the ring is
3E along KO
E along OK
E along KO
E along KO
A particle moves in a straight line with a constant acceleration. It changes its velocity from 10 ms-1 to 20 ms-1 while passing through a distance 135 m in t second. The value of t is
10
1.8
12
12
D.
12
The problem requires kinematics equations of motion
Let u and v be the first and final velocities of particle an a and s be the constant acceleration and distance covered by it.
From third equation of motion
v2 = u2 + 2as
(20)2 = (10)2 + 2a x 135
or
a = 300/2 x135 = 10/9 ms-2
Now using first equation of motion,
A thin rod of length L and Mass M is bent at its midpoint into two halves so that the angle between them is 90o. The moment of inertia of the bent rod about an axis passing through the bending point and perpendicular to the plane defined by the two halves of the rod is
ML2/24
ML2/12
ML2/6
ML2/6
A particle of mass is projected with the velocity v making an angle of 45o with the horizontal.
When the particle lands on the level ground the magnitude of the change in its momentum will be
2 mv
Sand is being dropped on a conveyor belt at the rate of M kg/s. The force necessary to keep the belt moving with a constant velocity of v m/s will be
Mv newton
2 Mv newton
Mv/2 Newton
Mv/2 Newton
Which two of the following five physical parameters have the same dimensions?
1) Energy density
2) refractive index
3) dielectric constant
4) Young's modulus
5) Magnetic field
2 and 4
3 and 5
1 and 4
1 and 4
On a new scale of temperature (which is linear), an called the W scale, the freezing and boiling point of water are 39o W and 239o W respectively. what will be the temperature of 39o C celsius scale?
78o W
117o C
200o C
200o C
If Q, E andW denote respectively the heat added, change in internal energy and the work done in a closed cycle process, then
W =0
Q = W = 0
E=0
E=0
Two simple harmonic motions of angular frequency 100 and 1000 rad s-1 have the same displacement amplitude. The ratio of their maximum acceleration is
1:10
1:102
1:103
1:103
An electric kettle takes 4 A current at 220 V. How much time will it take to boil 1 kg of water from temperature 200 C? The temperature boiling water is 100o C.
6.3 min
8.4 min
12.6 min
12.6 min