Give reasons for the following :
(1) It is advisable to fasten the seat belt while travelling in a running car .
(2) In a high jump , athletes jump on mattress.

A compass needle is placed near a current - carrying straight wire . State your observation for the following case and give reason for the same in each case : (1) Direction of electric current in the wire is increased . (2) Magnitude of electric current in the wire is increased . (3) Teh compass needle is displaced away from the straight wire .

Assertion :- In a head-on car collision passengers not wearing seat belt can be thrown through the wind shield. Reason :- In above case, passengers are in motion while the car comes to rest.

State which of the following are polynomials and which are not ? Give reasons. p^(-2)+1

State which of the following are polynomials and which are not ? Give reasons. 4z^(2)+1/7

Suppose while sitting in a parked car, you notice a jogger approaching towards you in the side view mirror of R = 2 m. If the jogger is running at a speed of 5 ms^(-1) , how fast the image of the jogger appear to move when the jogger is (a) 49 m, (b) 59 m away.

State which of the following statements are true and which are false ? Give reasons for your choice. (1)/(x^(2)-5x+6) is a quadratic polynomial.

Suppose while sitting in a parked car, you notice a jogger approaching towards you in the side view mirror of R = 2 m. If the jogger is running at a speed of 5 ms^(-1) , how fast the image of the jogger appear to move when the jogger is (a) 39 m, (b) 29 m, (c) 19 m, and (d) 9 m away.

Answer carefully: (a) Two large conducting spheres carrying charges Q_(1) and Q_(2) are brought close to each other. Is the magnitude of electrostatic force between them exactly given by Q_(1),Q_(2)//4pi epsilon_(0)r^(2) , where r is the distance between their centres? (b) If Coulomb’s law involved 1//r^(3) dependence (instead of would Gauss’s law be still true ? (c) A small test charge is released at rest at a point in an electrostatic field configuration. Will it travel along the field line passing through that point? (d) What is the work done by the field of a nucleus in a complete circular orbit of the electron? What if the orbit is elliptical? (e) We know that electric field is discontinuous across the surface of a charged conductor. Is electric potential also discontinuous there? (f) What meaning would you give to the capacitance of a single conductor? (g) Guess a possible reason why water has a much greater dielectric constant (= 80) than say, mica (= 6).