KERALA PSC / PHYSICS / MOTION / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE / KERALA PSC PRELIMINARY / NOTES

 

KERALA PSC / PHYSICS / MOTION / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE / KERALA PSC PRELIMINARY / NOTES

KERALA PSC / PHYSICS / MOTION / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE / KERALA PSC PRELIMINARY / NOTES

·      The position of an object in space changes with time relative to an observer it is said to be in motion.

·      The actual length of path travelled by a body is called the distance covered by a body.

·      The shortest distance from the initial to the final position of a body is called displacement of the body. It does not depend on the actual path undertaken by the object

·      If the motion of an object is restricted to a straight line: it is a one dimensional motion. Eg: train running along a straight track.

·      If the motion of an object is restricted to a plane: it is a two dimensional motion. Eg: motion of a boat on a lake, a coin along a surface

·      Motion of projectiles, satellites, motion of charged particles in electric and magnetic fields are examples of two dimensional motion.

·      An object moving in space is said to be in three dimensional motion. Eg: A butterfly flying in air or motion of gas molecules in space.

·      Physical quantities that have only magnitude and no direction are called scalar quantities. Eg: Distance, speed, time, work, mass, density, temperature etc…

·      Physical quantities that have both magnitude and direction are called vector quantities. Eg: Displacement, weight, velocity, acceleration etc…

·      Speed is the distance travelled by a body in unit time. It is a scalar quantity. Its unit is m/s

·      Velocity is the displacement per unit time. It is a vector quantity and its unit is m/s

·      Acceleration is the rate of change of velocity. It is a vector quantity and its unit is m/s²

·      A decrease in the velocity with time is called deceleration or retardation. It is otherwise known as negative acceleration.

·      If the acceleration remains constant, ie., it does not change with time it is said to be uniform acceleration.

·      Projectile is the name given to a body which after having been given an initial velocity is allowed to move under the influence of gravity alone.

·      The path of the projectile is called trajectory

·      The trajectory of a projectile moving under the influence of a constant acceleration is a parabola.

·      A projectile has maximum range when the angle of projection is 45⁰.

·      The product of mass and its linear velocity is called linear momentum of the body. Unit of linear momentum is kg m/s.

·      The earth attracts everybody towards its centre. The acceleration with which freely falling bodies are attracted towards the earth is called the acceleration due to gravity. It is same for all bodies and its value is 9.81 m/s.

·      Newton’s first Law of Motion: Everybody continues in its state of rest or uniform motion in a straight line unless compelled by an external unbalanced force to change that state.

·      Second Law: The rate of change of momentum is directly proportional to the external unbalanced force and takes place in the direction of the force.

·      Third Law: To every action there is an equal and an opposite reaction.

·      Action and reaction are equal and opposite but they never cancel each other as they act on different objects

·      Rockets works according to Newton’s third law.

·      Inertia is the tendency of a body to continue in its state of rest or the state of uniform motion along a straight line.

·      Galileo discovered law of inertia.

·      An athlete run some distance before taking a long jump, by running the athlete gives himself larger inertia of motion.

·      As the train starts moving, a man sitting inside leans backwards because of inertia of rest.

·      When a shot is fired from a gun, the gun recoils due to the reaction force applied by the shot on the gun.

·      The branch of science which deals with the study of relative movement of interacting surfaces is called tribology

·      In order to increase stability, a person climbing a hill bends forward.

·      The flying of birds is a consequence of Newton’s third law of motion.   

  

KERALA PSC / PHYSICS / MOTION / OBJECTIVE QUESTIONS / STUDY MATERIALS / GENERAL KNOWLEDGE / KERALA PSC PRELIMINARY / NOTES