11. Mention any two sources of systematic errors.
12. Distinguish between path length and displacement.
13. Define relative velocity. Write the expression for relative velocity between two objects moving in same
direction.
14. State and explain the law of parallelogram of vector addition.
15. Mention any two advantages of friction.
Answers
Answer:
11) The two sources of systematic errors are (i) instrumental error (ii) personal error . Assertion : Systematic errors and random errors fall in the same group of errors.
12) Path Length Displacement
(i) The distance travelled by the body is called path length (i) The difference between the initial and the final positions of a body is called its displacement.
(ii) It is a scalar quantity. (ii) It is a vector quantity.
(iii) It can never be 0 or negative. (iii) It can be 0 or negative.
13) Relative velocity is a difference in velocities of two objects where one is at rest with respect to another. It can be expressed as V = Vab + Vbc when two bodies are in same direction.
14) According to the parallelogram law of vector addition if two vectors act along two adjacent sides of a parallelogram(having magnitude equal to the length of the sides) both pointing away from the common vertex, then the resultant is represented by the diagonal of the parallelogram passing through the same common vertex.
15) Friction is responsible for many types of motion.
It helps us walk on the ground.
Brakes in a car make use of friction to stop the car.
Asteroids are burnt in the atmosphere before reaching Earth due to friction.
It helps in the generation of heat when we rub our hands.
Explanation:
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