CBSE 11TH PHYSICS - Online Test

Answer : Option D
Explaination / Solution:

kinetic energy is transferred to other forms of energy—such as thermal energy, potential energy, and sound—during the collision process. After collision if recovery of kinetic energy is 100% then it is called elastic collision.So that in an elastic collision the total kinetic energy of the system is the same after the collision as before.

Answer : Option D
Explaination / Solution:
No Explaination.

Answer : Option B
Explaination / Solution:

it is impossible to devise a cyclically operating device, the sole effect of which is to absorb energy in the form of heat from a single thermal reservoir and to deliver an equivalent amount of work. This implies that it is impossible to build a heat engine that has 100% thermal efficiency.

Answer : Option C
Explaination / Solution:

F = mg = 0.05 x 10 = 0.5 N

Answer : Option C
Explaination / Solution:

Universal law of Gravitational explain the force of attraction between two bodies having mass  and placed at a distance but it never explain how this force generated and what is the origin of this.

Answer : Option C
Explaination / Solution:

As the child stand up then Centre of mass is shifted in upwards direction from the sitting position of child, thus decreasing the effective length of  the swing, so as the time period is proportion to square root of length, thus time period decreases.

time period 

T=2πlg−−√T∝l√

Time period of swing decreases as effective length decreases.

Answer : Option A
Explaination / Solution:

It is a dimension less number comprised of the physical characteristics of the flow. An increasing Reynolds number indicates an increasing turbulence of flow.

It is defined as: Re
$R_e=$ρvDη

where;
v is the flow velocity
D is a characteristic linear dimension
ρ fluid density(kg/m3)
η$\eta$ is dynamic viscosity (Pa.s)
ν kinematic viscosity (m2/s),  
$v=$ηρ

Answer : Option D
Explaination / Solution:

for 1 mole of ideal gas, according to ideal gas equation

PV=RTPVT=R=const.

hence graph must be with zero slope. So that dotted line show ‘ideal’ gas behavior and curved line shows deviation from ‘ideal’ gas behavior

Answer : Option D
Explaination / Solution:

Convection is the heat transfer due to bulk movement of molecules within fluids.

Answer : Option C
Explaination / Solution:

Dimensional Analysis (also called Factor-Label Method or the Unit Factor Method) is a problem-solving method that uses the fact that any number or expression can be multiplied by one without changing its value. It is a useful technique. Another use of dimensional analysis is in checking the correctness of an equation which you have derived after some algebraic manipulation. Even a minor error in algebra can be detected because it will often result in an equation which is dimensionally incorrect.