Answer:
C. 1) No Change (4 sec) 2) 5.7 sec 3) 2.8 sec 4) No Change (4 sec)
Explanation:
Given that:
Period (T) = 4 s
1) If the mass is doubled.
The period of a pendulum is given by the formula:
where L is the length and g is the acceleration due to gravity.
From the formula, the period does not depend on the mass of the spring therefore if the mass is doubled the period does not change.
2) The string length is doubled
Given that:

if the length is doubled, the new spring length is 2L. Therefore the new period (T1) is given as:

3) The string length is halved
Given that:

if the length is halved, the new spring length is L/2. Therefore the new period (T1) is given as:

4) The amplitude is halved
From the formula, the period does not depend on the amplitude therefore if the amplitude is halved the period does not change.
Answer:
Explanation:
The sealed bottle serves as an open system for the water molecules, thus heat energy can be exchanged with its surroundings. When the bottle is placed in a warm environment, there would be a gradual increase in the thermal energy of the molecules of water due to a change in the temperature of its surroundings.
Thus, the molecules of water closer to the boundary of the bottle absorbs heat, becomes lighter and changes position. This gradual process continues until all molecules attains an average temperature which equals that of the surroundings of the bottle.
Therefore, both the thermal energy and temperature of the water increases.
<span>since sound travels using mechanical waves and needs a material medium to propagate and since mechanical waves spread through vibrations ...and since hard materials have their atoms packed closely....they need to vibrate with a smaller amplitude to pass on the wave....thus sound travels faster in a denser medium than a less dense one.</span>