Q.1.What is gravity?
Ans. The force of attraction between the earth and a body is called gravity.
Q.2. What is gravitation?
Ans. The force of attraction between two bodies is called gravitation
Q.3. If the earth suddenly stops rotating about its axis, what should be the effect on '? Would this offect be same at all places?
Ans. The value of g decreases due to rotation of the earth, the effect is maximum at equator & minimum at poles. Therefore, if the earth stops rotating, the value of g would increase and the effect observed would be maximum at equator.
Q4. What is the necessary and sufficient condition for a motion to be simple harmonic?
Ans. The condition is that the restoring force must be proportional to displacement of particle from equilibrium position.
Q.5. When will the motion of a simple pendulum be Simple harmonic?
Ans. The motion of a simple pendulum will be simple harmonic,
when the amplitude of motion is very small such that the
approximation Sine = 0 always holds.
Q.6. On what factors does the period of a simple pendulum depend?
Ans. The period of a simple pendulum depends only on effective length / and acceleration to gravity g for small amplitude of oscillations
Q.7. What is Moment of Inertia?
Ans. The moment of inertia of a system of particles (or a body) about an axis is defined as the sum of products of masses and the square of the distances of particles constituting the system (or body) from the axis. Le Moment of inertia | Emr2
Q.8. Is it a scalar or a vector or a tensor quantity ?
Ans: It is a tensor quantity.
Q.9. What is its unit?
Ans. Its unit is Kg-Meter
Q.10. What is Radius of gyration?
Ans. It may be defined as the perpendicular distance from the axix of rotation, the square of which when multiplied with the total mass of the body, gives the moment of inertia of the body about the axis
i.e. I=MK2, K being radius of gyration.
Q.11. What is the expression for Rotational Kinetic Energy?
Ans. The expression for Rotational kinetic energy is given by
Rot KE = 1/2Iw², Symbols have their usual meaning.
Q.12. What is the theorem of parallel axes?
Ans. This theorem states that the moment of inertia of a body about any axis is equal to its moment of inertia about a parallel axis through its centre of mass plus the product of the mass of the body and square of perpendicular distance between the two axes: i.e. I=IG+Mr2
Where IG= M.I. about an axis passing through centre of gravity,
M= Total mass of the body and I = M.I. about a parallel axis at a distance r from that passing through centre of gravity.
Q.13. What is the theorem of perper dicular axes?
Ans. This theorem states that the sum of the moments of inertia of a plane lamina about any two mutually perpendicular axes in its plane is equal to its moment of inertia about an axis perpendicular to the plane of the lamina and passing through the point of intersection of the first two axes,
i.e. Iz = Ix+Iy Where X,Y,Z, axes are mutually perpendicular axes.
Ans. The force of attraction between the earth and a body is called gravity.
Q.2. What is gravitation?
Ans. The force of attraction between two bodies is called gravitation
Q.3. If the earth suddenly stops rotating about its axis, what should be the effect on '? Would this offect be same at all places?
Ans. The value of g decreases due to rotation of the earth, the effect is maximum at equator & minimum at poles. Therefore, if the earth stops rotating, the value of g would increase and the effect observed would be maximum at equator.
Q4. What is the necessary and sufficient condition for a motion to be simple harmonic?
Ans. The condition is that the restoring force must be proportional to displacement of particle from equilibrium position.
Q.5. When will the motion of a simple pendulum be Simple harmonic?
Ans. The motion of a simple pendulum will be simple harmonic,
when the amplitude of motion is very small such that the
approximation Sine = 0 always holds.
Q.6. On what factors does the period of a simple pendulum depend?
Ans. The period of a simple pendulum depends only on effective length / and acceleration to gravity g for small amplitude of oscillations
Q.7. What is Moment of Inertia?
Ans. The moment of inertia of a system of particles (or a body) about an axis is defined as the sum of products of masses and the square of the distances of particles constituting the system (or body) from the axis. Le Moment of inertia | Emr2
Q.8. Is it a scalar or a vector or a tensor quantity ?
Ans: It is a tensor quantity.
Q.9. What is its unit?
Ans. Its unit is Kg-Meter
Q.10. What is Radius of gyration?
Ans. It may be defined as the perpendicular distance from the axix of rotation, the square of which when multiplied with the total mass of the body, gives the moment of inertia of the body about the axis
i.e. I=MK2, K being radius of gyration.
Q.11. What is the expression for Rotational Kinetic Energy?
Ans. The expression for Rotational kinetic energy is given by
Rot KE = 1/2Iw², Symbols have their usual meaning.
Q.12. What is the theorem of parallel axes?
Ans. This theorem states that the moment of inertia of a body about any axis is equal to its moment of inertia about a parallel axis through its centre of mass plus the product of the mass of the body and square of perpendicular distance between the two axes: i.e. I=IG+Mr2
Where IG= M.I. about an axis passing through centre of gravity,
M= Total mass of the body and I = M.I. about a parallel axis at a distance r from that passing through centre of gravity.
Q.13. What is the theorem of perper dicular axes?
Ans. This theorem states that the sum of the moments of inertia of a plane lamina about any two mutually perpendicular axes in its plane is equal to its moment of inertia about an axis perpendicular to the plane of the lamina and passing through the point of intersection of the first two axes,
i.e. Iz = Ix+Iy Where X,Y,Z, axes are mutually perpendicular axes.
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