Answer:
Solids
:A solid has a definite shape and volume because the molecules that make up the solid are packed closely together and move slowly. Solids are often crystalline; examples of crystalline solids include table salt, sugar, diamonds, and many other minerals. Solids are sometimes formed when liquids or gases are cooled; ice is an example of a cooled liquid which has become solid. Other examples of solids include wood, metal, and rock at room temperature. Liquids
: A liquid has a definite volume but takes the shape of its container. Examples of liquids include water and oil. Gases may liquefy when they cool, as is the case with water vapor. This occurs as the molecules in the gas slow down and lose energy. Solids may liquefy when they heat up; molten lava is an example of solid rock which has liquefied as a result of intense heat. Gases
: A gas has neither a definite volume nor a definite shape. Some gases can be seen and felt, while others are intangible for human beings. Examples of gases are air, oxygen, and helium. Earth's atmosphere is made up of gases including nitrogen, oxygen, and carbon dioxide. Plasma: Plasma has neither a definite volume nor a definite shape. Plasma often is seen in ionized gases, but it is distinct from a gas because it possesses unique properties. Free electrical charges (not bound to atoms or ions) cause the plasma to be electrically conductive. The plasma may be formed by heating and ionizing a gas. Examples of plasma include stars, lightning, fluorescent lights, and neon signs.
Explanation:
Answer: The person sitting in the middle of the train sees the back of the train enter ing the tunnel before the front end comes out.
Explanation:
Answer:
Explanation:
To solve this problem, we can use the following suvat equation:
where
is the vertical displacement of the frog
is the initial vertical velocity
t is the time
a is the acceleration
We have chosen this formula because apart from , all the other quantities are known. In fact:
is the vertical displacement
t = 2 s is the total time of flight
is the acceleration due to gravity (negative because it is downward)
Therefore, solving for , we find the initial velocity of the frog:
Answer:
Anna is correct.
Explanation:
Anna is right as a satellite is in free fall because it keeps falling toward Earth, meaning that gravity is the only force acting on it. Tom is incorrect because an object does not have to accelerate at a certain speed to be considered to be in free fall. As long as gravity is the only force acting upon the object, it is considered to be in free fall.
