Fluid Mechanics — JEE physics STD 12 Science — Question

Assertion : A spring has potential energy, both when it is compressed or stretched.
Reason : In compressing or stretching, work is done on the spring against the restoring force.

Assertion : Power of machine gun is determined by both, the number of bullet fired per second and kinetic energy of bullets.
Reason : Power of any machine is defined as work done (by it) per unit time.

Assertion : Electromagnets are made of soft iron.
Reason : Coercivity of soft iron is small.

Assertion : The absorbance of a perfect black body is unity.
Reason : A perfect black body when heated emits radiations of all possible wavelengths at that temperature.

Assertion : The work done during a round trip is always zero.
Reason : No force is required to move a body in its round trip.

Assertion : Two persons on the surface of moon cannot talk to each other.
Reason : There is no atmosphere on moon.

Assertion : Air quickly leaking out of a balloon becomes coolers
Reason : The leaking air undergoes adiabatic expansion.

Assertion : Only microwaves are used in radar.
Reason : Because microwaves have very small wavelength.

Assertion : Water at the foot of the water fall is always at different temperature from that at the top.
Reason : The potential energy of water at the top is converted into heat energy during falling.

Assertion : Two particles of different mass, projected with same velocity at same angles. The maximum height attained by both the particle will be same.
Reason : The maximum height of projectile is independent of particle mass.