Answer:
The speed of the stone just before it hits the ground is 18.54 m/s
Explanation:
Given that,
Initial speed of the stone, u = 8 m/s
The stone is thrown downward from a height of 14 m
We need to find the speed of the stone just before it hits the ground. It can be calculated using third equation of motion as :

v is the speed of the stone just before it hits the ground


v = 18.54 m/s
So, the speed of the stone just before it hits the ground is 18.54 m/s. Hence, this is the required solution.
Answer:
sound wave-electrical wave-radio wave
During a phase change, the temperature remains constant. obviously all the heat is used in phase transformation.
Answer:
Energy absorbed or hidden when water evaporates
Explanation:
The heat that is required to make a phase change is known as latent heat.
A phase change occurs when matter changes state. For example from solid to liquid, from liquid to gas, among others.
When changing from liquid to gas (for example when water evaporates), the heat necessary for this to happen is called latent heat of vaporization. The word latent means hidden, because a change in temperature is not perceived during the phase change, even when heat is being added, thus it is said that the heat is hidden or latent.
So the answer is:
- Energy absorbed or hidden when water evaporates.
*Another type of latent heat is the latent heat of fusion, which is when a solid becomes liquid.
The amount of energy needed to increase the temperature of a substance by

is given by

where
m is the mass of the substance

is its specific heat capacity

is the increase in temperature
The water volume is

, since its density is

, the mass of this sample of water is

The water specific heat capacity is

and the increase in temperature is

Therefore, the amount of energy needed is