DSSSB PGT Physics Mock Test - 2 - DSSSB TGT/PGT/PRT MCQ

'P of Q + R' means Q is the father of P, R is the daughter of Q.

Hence, R is the sister of P.

Angular acceleration. Angular acceleration is the rate of change of angular velocity. In three dimensions, it is a pseudovector. In SI units, it is measured in radians per second squared (rad/s²), and is usually denoted by the Greek letter alpha (α).

For a person to catch the ball they should travel the same distance along the horizontal axis in time T.
Distance covered by person, R 


 

Uniform force acting = 3i + j N
Displacement done = (4-2)i + 3j + (-1-1)k
= 2i + 3j -2k
Thus total work done = F.s (dot product here)
We get W = 3 x 2 + 1 x 3 + 0 x -2
= 9J

The path of a projectile under the influence of gravity is a parabola. This is derived from the kinematic equations of motion in two dimensions:

• The horizontal motion is uniform (constant velocity).
• The vertical motion is uniformly accelerated (due to gravity).

Combining these motions, the equation of the trajectory is:

This equation represents a parabolic path, where θ is the angle of projection, u is the initial velocity, and g is the acceleration due to gravity.

Thus, the trajectory of a projectile is a parabola.

Resultant force is zero, as three forces on the particle can be represented in magnitude and direction by three sides of a       triangle in same order. Hence, by Newton's 2nd law 

Particle velocity  will be same

Let mass of the block be m.

Frictional force in rest position F = mg sin 30⁰

[This is static frictional force and may be less than the limiting frictional force]

When the body is in rest it is under static friction but when it starts moving (neither rolling nor sliding), the static friction slowly chngs to kinetic friction as the coefficient of static friction start decreasing and that of kinetic friction starts increasing. In case it starts rolling motion then the friction is rolling friction & if it slides then sliding fiction.

Since collision is elastic and mass is same then after velocity exchange A body will stop and B will start moving with A's velocity in the same direction.

We know that for a spring with spring constant k, work done by the spring when a compression or expansion is done of some length say x is ½ kx²
Also as the work done is in the opposite direction to that of force applied, we get the sign of the force to be negative.

On solving we get 3L/4
 

Hence v = v/4
 

Concept 

Newton's law of gravitation states "Every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres."

Explanation 

Newton's law of gravitation can be represented mathematically as: F = G x (m₁ x m₂/ r²)

Where:

• F is the force of attraction between the two bodies.
• m₁ and m₂ are the masses of the two bodies.
• r is the distance between the centres of the two bodies.
• G is the gravitational constant, a proportional constant that in the SI system is approximately 6.674 x10^-11N(m/kg)².
• So, if you have two bodies with masses m1 and m2, and they are separated by a distance r, then the force of gravity between them is directly proportional to the product of their masses and inversely proportional to the square of the distance between them,
• Real-world applications of this law include everything from explaining the motion of planets in our solar system to the rolling of a ball down a hill. It's one of the cornerstones of classical physics and is essential in understanding the larger structure of the universe.

Concept:

Newton's law of gravitation: The force of attraction between any objects in the universe is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

• The force acts along the line joining the two bodies.
• The gravitational force is a central force that is It acts along the line joining the centers of two bodies.
• It is a conservative force. This means that the work done by the gravitational force in displacing a body from one point to another is only dependent on the initial and final positions of the body and is independent of the path followed.

Explanation:

• The gravitational force on mercury due to the sun is very large than that due to the earth.
• As observed from the earth, the sun appears to move around the earth in a circular orbit though, in reality, the earth moves around the sun due to gravitational force between them
• All planets move around the sun due to the huge gravitational force of the sun acting on them.
• Since the gravitational force on mercury due to the earth is smaller as compared to that on it due to the sun therefore it revolves around the sun and not around the earth.

Hence, option (3) is the correct answer.

When liquid molecules are attracted strongly to themselves and weakly to those of solids, it costs lots of energy to create liquid-solid surface and liquid then does not wet the solid.
For Example: Mercury molecules (which make an obtuse angle with glass) have a strong force of attraction between themselves and a weak force of attraction toward solids. Hence, they tend to form drops. 
On the other hand, water molecules make acute angles with glass. They have a weak force of attraction between themselves and a strong force of attraction toward solids. Hence, they tend to spread out.

In 9s, the distance travelled = 4A × 3 = 12A 

Imagine, now it is at

The phenomenon of interference is based on the principle of superposition.

According to Gauss’s Law, the total number of electric field lines coming out of a charge q is =where εo is the absolute permittivity of air. Its value is 8.85 * 10^-12. Therefore the number of lines coming out from a 1C charge = 1/8.85 * 10^-12.

The standard convention states that the electric potential at a point infinitely far from a charge is considered to be:

• Zero

This means that as you move further away from a charge, the potential energy associated with that charge diminishes to zero.

From conservation of angular momentum, 
mr₀ = r/2 = mvr
⇒ v = v₀/2
From conservation of energy,

The circuit is symmetrical about the axis POQ.
The circuit above the axis POQ represents balanced wheatstone bride. Hence the central resistance 2R is ineffective. Similarly in the lower part (below the axis POQ) the central resistance 2R is ineffective.

Therefore the equivalent circuit is drawn.

At null point

If radius of the wire is doubled, then the resistance of AC will change and also the resistance of CB will change. But since R₁/R₂ does not change so, R₃/R₄
 should also not change at null point. Therefore the point C does not change.

KEY CONCEPT : When a charged particle is moving at right angles to the magnetic field then a force acts on it which behaves as a centripetal force and moves the particle in circular motion.

The wire carries a current I in the negative z-direction.
We have to consider the magnetic vector field

Magnetic field is perpendicular to OP.

Paramagnetic materials are those when suspended freely inside the magnetic field, it slowly sets itself parallel to the direction of the magnetic field. When placed in a non-uniform magnetic field, it tends to move from weaker to a stronger magnetic field.

At any time, t
energy stored in capacitor, EC=q²/2C
Total energy stored in C and L at any time t
E=E_C+E_L
E=(q²/2C)+(LI²/2)
If q=q₀sinωt
I=dq/dt=q₀cosωtω=ωq0cosωt
Put in (i), E=[(q₀sinωt)²/2C] + L(ωq₀cosωt)²/2
E=(q₀²/2C) sin²ωt+(q₀²/2)cos2ωt.ω²L
But ω²=12/LC
∴E=(q₀²/2C) sin²ωt+(q₀²/2) (L/LC) cos²ωt
=q₀²/2C(sin²ωt+cos²ωt)
=q₀²/2C= constant in time.
 

The shape of the wave front in case of a light diverging from a point source is spherical and is shown in the given figure. The shape of the wavefront in case of a light emerging out of a convex lens when a point source is placed at its focus is a parallel grid.

Hence, the maximum velocity with which a vehicle can go round a level curve, without skidding is Here, r = 40 m