Magnetism — JEE physics STD 12 Science — Question

Assertion : A body can have acceleration even if its velocity is zero at a given instant of time.
Reason : A body is momentarily at rest when it reverses its direction of motion.

Assertion : Machine parts are jammed in winter.
Reason : The viscosity of lubricant used in machine parts increase at low temperature.

Assertion : A piece of red glass is heated till it glows in dark. The colour of glowing glass would be orange.
Reason : Red and orange is complementary colours.

Assertion : The periodic time of a hard spring is less as compared to that of a soft spring.
Reason : The periodic time depends upon the spring constant, and spring constant is large for hard spring.

Assertion : We can not change the temperature of a body without giving (or taking) heat to (or from) it.
Reason : According to principle of conservation of energy, total energy of a system should remains conserved.

Assertion : Environmental damage has increased the amount of ozone in the atmosphere.
Reason : Increase of ozone increases the amount of ultraviolet radiation on earth.

Assertion : First law of thermodynamics is a restatement of the principle of conservation
Reason : Energy is fundamental quantity.

Assertion : Aeroplanes always fly at low altitudes.
Reason : According to Newton's third law of motion, for every action there is an equal and opposite reaction.

Assertion : A force act upon the earth revolving in a circular orbit about the sun. Hence work should be done on the earth.
Reason : The necessary centripetal force for circular motion of earth comes from the gravitational force between earth and sun.