Physics-

General

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### Question

#### A thin uniform annular disc (see figure) of mass has outer radius and inner radius . The work required to take a unit mass from point on its axis to infinity is

#### The correct answer is:

Potential at point will be obtained by in integration as given below. Let be the mass of small rings as shown

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### Related Questions to study

physics-

#### The two bodies of mass and respectively are tied to the ends of a massless string, which passes over a light and frictionless pulley. The masses are initially at rest and the released. Then acceleration of the centre of mass of the system is

In the pulley arrangement

But is in downward direction and in the upward direction ,

Acceleration of centre of mass

But is in downward direction and in the upward direction ,

Acceleration of centre of mass

#### The two bodies of mass and respectively are tied to the ends of a massless string, which passes over a light and frictionless pulley. The masses are initially at rest and the released. Then acceleration of the centre of mass of the system is

physics-General

In the pulley arrangement

But is in downward direction and in the upward direction ,

Acceleration of centre of mass

But is in downward direction and in the upward direction ,

Acceleration of centre of mass

maths-

#### If to terms, terms, , then

#### If to terms, terms, , then

maths-General

Maths-

#### The coefficient of in is

#### The coefficient of in is

Maths-General

maths-

maths-General

chemistry-

#### Compounds (A) and (B) are –

#### Compounds (A) and (B) are –

chemistry-General

Maths-

Maths-General

maths-

A triangle is inscribed in a circle. The vertices of the triangle divide the circle into three arcs of length 3, 4 and 5 units. Then area of the triangle is equal to:

A triangle is inscribed in a circle. The vertices of the triangle divide the circle into three arcs of length 3, 4 and 5 units. Then area of the triangle is equal to:

maths-General

Maths-

#### If one root of the equation is reciprocal of the one of the roots of equation then

#### If one root of the equation is reciprocal of the one of the roots of equation then

Maths-General

Maths-

#### If the quadratic equation and have a common root then is equal to

#### If the quadratic equation and have a common root then is equal to

Maths-General

physics-

#### Two blocks of masses 10 kg and 4 kg are connected by a spring of negligible mass and placed on frictionless horizontal surface. An impulsive force gives a velocity of 14 to the heavier block in the direction of the lighter block. The velocity of centre of mass of the system at that very moment is

At the time of applying the impulsive force block of 10 kg pushes the spring forward but 4 kg mass is at rest.

Hence,

Hence,

#### Two blocks of masses 10 kg and 4 kg are connected by a spring of negligible mass and placed on frictionless horizontal surface. An impulsive force gives a velocity of 14 to the heavier block in the direction of the lighter block. The velocity of centre of mass of the system at that very moment is

physics-General

At the time of applying the impulsive force block of 10 kg pushes the spring forward but 4 kg mass is at rest.

Hence,

Hence,

Maths-

#### In a Δabc if b+c=3a then has the value equal to –

#### In a Δabc if b+c=3a then has the value equal to –

Maths-General

Maths-

#### In a simplifies to

#### In a simplifies to

Maths-General

Maths-

#### In a triangle ABC, a: b: c = 4: 5: 6. Then 3A + B equals to :

#### In a triangle ABC, a: b: c = 4: 5: 6. Then 3A + B equals to :

Maths-General

physics-

#### A bullet of mass is fired with a velocity of 50 at an angle with the horizontal. At the highest point of its trajectory, it collides had on with a bob of massless string of length m and gets embedded in the bob. After the collision, the string moves to an angle of 120. What is the angle

Velocity of bullet at highest point of its trajectory = 50 in horizontal direction.

As bullet of mass collides with pendulum bob of mass 3 and two stick together, their common velocity

As now under this velocity pendulum bob goes up to an angel 120, hence

or

Comparing two answer of , we get

or

As bullet of mass collides with pendulum bob of mass 3 and two stick together, their common velocity

As now under this velocity pendulum bob goes up to an angel 120, hence

or

Comparing two answer of , we get

or

#### A bullet of mass is fired with a velocity of 50 at an angle with the horizontal. At the highest point of its trajectory, it collides had on with a bob of massless string of length m and gets embedded in the bob. After the collision, the string moves to an angle of 120. What is the angle

physics-General

Velocity of bullet at highest point of its trajectory = 50 in horizontal direction.

As bullet of mass collides with pendulum bob of mass 3 and two stick together, their common velocity

As now under this velocity pendulum bob goes up to an angel 120, hence

or

Comparing two answer of , we get

or

As bullet of mass collides with pendulum bob of mass 3 and two stick together, their common velocity

As now under this velocity pendulum bob goes up to an angel 120, hence

or

Comparing two answer of , we get

or

physics-

#### A spherical hollow is made in a lead sphere of radius such that its surface touches the outside surface of lead sphere and passes through the centre. What is the shift in the centre of lead sphere as a result of this hollowing?

Let centre of mass of lead sphere after hollowing be at point where

Mass of spherical hollow and

shift

Mass of spherical hollow and

shift

#### A spherical hollow is made in a lead sphere of radius such that its surface touches the outside surface of lead sphere and passes through the centre. What is the shift in the centre of lead sphere as a result of this hollowing?

physics-General

Let centre of mass of lead sphere after hollowing be at point where

Mass of spherical hollow and

shift

Mass of spherical hollow and

shift