CBSE 11TH PHYSICS - Online Test

Answer : Option C
Explaination / Solution:

Moment of inertia of ring or circular loop about axis passing through centre of mass and perpendicular to plane is MR2 ,

Applying perpendicular axis theorm 

Iz=Ix+IyMR2=I+II=12MR2

Here I = Moment of inertia about axis passing through diameter

As  moment of inertia in terms of radius of gyration (k)  is Mk2

I = Mk2

12MR2=Mk2k=R/2–√

Answer : Option C
Explaination / Solution:

Capillary action(sometimes capillarity or wicking) is the ability of a liquid to flow in narrow spaces without the assistance of,or even in opposition to, external forces like gravity. The effect can be seen in the drawing up of liquids between the hairs of a paint-brush, in porous materials such as paper and plaster, in some non-porous materials such as sand and liquefied carbon fiber, or in a cell. It occurs because of intermolecular forces between the liquid and surrounding solid surfaces. If the diameter of the tube is sufficiently small, then the combination of surface tension (which is caused by cohesion within the liquid) and adhesive forces between the liquid and container wall act to propel the liquid.

Answer : Option D
Explaination / Solution:

E=32kT=32×1.38×10−23×300=6.2×10−21J

k = boltzman constant

Answer : Option D
Explaination / Solution:

E=32kT

Answer : Option A
Explaination / Solution:

Pressure is not the same physical thing as stress, but they do use the same definition and thus produce the same units, so the same calculator can be used for both. They both measure force per unit area. SI unit of both pressure and stress is Pascal.

Answer : Option D
Explaination / Solution:
No Explaination.

Answer : Option D
Explaination / Solution:

Relative velocity of a body A with respect to another body B, when both are in motion, is the velocity with which A appears to move to B.

In general,

VBA=VB−VA

Answer : Option B
Explaination / Solution:
No Explaination.

Answer : Option B
Explaination / Solution:

Work done=mgh1+hRIf h=R then,⇒Work done=mgh1+RR=12mgh

Answer : Option D
Explaination / Solution:

(a) displacement is shortest distance b/w initial point and final point, as he returns back to origin after starting from origin, the displacement is zero. 

(b) Average velocity = Displacementtime taken

As displacement is zero, so average velocity is also eqaul to zero.

(c) Radius r = 1 km

distance covered = OP+PQ+QO

 =r+2πr4+r=2r+2πr4

= 2×1+(24×227×1)

= 257$\frac{25}{7}$km

Time taken = 10 minutes = 16$\frac{1}{6}$hour 

Average speed  =25716=25×67$=$

21.4 km/h