CBSE 11TH PHYSICS - Online Test

Answer : Option A
Explaination / Solution:

a heat engine converts heat energy to mechanical work by using the temperature difference between a hot "source" and a cold "sink". Heat is transferred from the source, through the "working body" of the engine, to the "sink", and in this process some of the heat changes into work by using the qualities of the gas or liquid inside the engine.

Answer : Option D
Explaination / Solution:

In ohysics, we can neglect some small forces, quantities and calculation.

Answer : Option D
Explaination / Solution:

As the area of contact is less in the case of rolling than in the case of sliding. In rolling surface of contact do not rub each other. The velocity of the point of contact with respect to the surface remains zero all the time although the Centre of mass of the wheel moves forward. Hence rolling friction is negligible in comparison to static friction.

Answer : Option C
Explaination / Solution:

According to perpendicular axis  theorem "For a planar object, the moment of inertia about an axis perpendicular to the plane is the sum of the moments of inertia of two perpendicular axes through the same point in the plane of the object".

Iz=Ix+Iy

Answer : Option C
Explaination / Solution:

This is the application of Bernoulli's Theorem. If air speeds up the pressure is lowered.Thus,a wing generates lift because the air goes faster over the top creating a region of low pressure,and thus lift.

Answer : Option C
Explaination / Solution:

We know that Yield strength times the Area give the weight of the body.

As Yield strength = weight of body/area

For safety purposes

Yield strength ≥ weight of body/area 

Sy ≥ Mg/A

A ≥Mg/ Sy

Answer : Option D
Explaination / Solution:

The specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius.

Answer : Option A
Explaination / Solution:

The relative error in a physical quantity raised to a power k is the k times the relative error in the individual quantity.

for e.g. x=anbm

maximun relative error, Δxx=±(nΔaa+mΔbb)

Answer : Option A
Explaination / Solution:

The damped natural frequency fd is related to the natural frequency fn by a  relation 

 fd=fn1−ζ2−−−−−√

where damping ratio ζ  is <= 1 

so the fd is less than the natural frequency 

Answer : Option D
Explaination / Solution:

When a satellite revolves around a planet in its orbit, it possesses both potential energy (due to its position against the gravitational pull of earth) and kinetic energy (due to orbital motion).

∴Total Energy = Potential Energy(U) + Kinetic Energy(K) = −GMmr+GMm2r = −GMm2r=−L22mr2

Hence we can say that total energy of circularly orbiting satellite is negative.