Answer
The same number of particles in a gas spread further apart than in the liquid or solid states.
Explanation:
The same number of particles in a gas spread further apart than in the liquid or solid states. The same mass takes up a bigger volume. This means the gas is less dense. Density also depends on the material.
Answer:
For Total energy and momentum to be conserved, the minimum energy of the photons released is equal to twice the rest mass energy of an electron that is 
The annihilation of electron -positron cannot produce a single photon. It is prohibited by the law of conservation of energy and momentum.
Answer:
sawing a board in half
dissolving sugar in water
a block of ice subliming
Explanation:
Answer:
The ball took 0.4 seconds
Explanation:
» From the second newton's equation of motion.

- s is displacement, s = 80cm, s = 0.8 meters
- u is initial velocity, u = 0 [ from rest ]
- g is 10 m/s²

Work is done when spring is extended or compressed. Elastic potential energy is stored in the spring. Provided inelastic deformation has not happened, the work done is equal to the elastic potential energy stored.