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Friction: The force which resists the motion of a body while moving on a surface is called friction. Some properties of friction: (i) Friction depends on the nature of surfaces in contact. (ii) Frictional force does not depends on the surface area. (iii) It is acts in a direction opposite to the direction of motion.

Cell: Structure and Function Brief History of Cell Discovery An English scientist, Robert Hooke, discover cell in 1665 . When he was examining a dried section of cork tree with his own made light microscope, he saw many honeycomb like empty chambers in it. He named each hollow space as cell. After his discovery of cell, considerable progress has been made in the development of powerful and more sophisticated microscopes. In 1831, Scottish scientist Robert Brown named nucleus of a cell. In 1839, Parkenje named Protoplasm . In 1839, Schleidon and Schwamm together announced cell theory -

Factorisation Factors: When an algebraic equation can be written as the product of two or more expressions then each of these is called a factor of the give equation. Factorisation: The process of finding two or more expressions whose product is the given expression is called factorisation.

C BSE Physics Class IX (9th) Motion Part 2 Uniform and Non-uniform Motion Uniform Motion : When a moving body always travels equal distance in equal interval of time, then its motion is called uniform motion. Example: If a car covered 5km distance in every hour, then its motion is called uniform motion. Non-uniform motion : When a body travels different distances in equal interval of time, then its motion is called non-uniform motion.

CBSE Physics Class IX (9th) Motion Motion : When an object change its position with respect to time and surrounding then the object is said to be in motion. Example: Moving car, bus etc since they change their position with respect to time. Rest : When an object does not change its position with respect to time and surrounding then the object is said to in rest.

CBSE Mathematics Class VIII (8 th ) MCQ Time and Work A alone can do a piece of work in 6 days and B alone can do it in 12 days. In how many days will A and B together do the same work? a.        2 days                   b. 3 days           c. 4 days          d. 5 days Answer:

CBSE Worksheet-01 CLASS – VIII Mathematics (Direct and Inverse Proportions) Choose the correct option: 1. If 14Kg of pulses cost Rs441, what is the cost of 22 Kg of pulses? a. Rs 627       b. Rs 649 c. Rs 671       d. Rs 693