Solids, liquids and gases

Question 1

Density

Answer 1

Density is a measure of the amount of mass packed into a particular volume

Question 1

Describe why the elephant does not sink in the sand and why the knife feels sharp. Make sure to mention force and area in your answers.

Answer 1

The elephant does not sink because the weights is spread out over the feet. The feet have a large surface area meaning there is going to be small pressure.

The knife feels sharp because there is at the edge there is a very small surface area, therefore when you apply the force you get a large pressure.

Question 2

Explain why the water shoots out further from hole C compared with hole A.
If there is a tank with 4 shoots, A is the top one C is the lower one close to ground.

Answer 2

The water jet from hole C shoots out further because there is a higher force being applied because there if more water on top of hole C than hole A. Therefore the weight of the water(gravity) if larger meaning the water would shoot out further.

Question 3

Why do dams have this shape? Thicker at bottom and thinner at top

Answer 3

Damps are thicker at the bottom to withstands the water pressure. This is because water pressure increases with death so at the bottom at the damp there is more pressure. Therefore the is more force pushing at the damp meaning it had to be thicker at the bottom.

Question 4

Presuure in gasses

Answer 4

Consider a gas in a container. It consists of a large number of particles moving at high speed in random directions.
As a particle strikes the side of a container it will rebound and produce a tiny force. This acts over the surface area of the container and hence a pressure is produced. If the volume of the container increases, the area of each wall increases and so the pressure decreases. If the temperature increases, the particles all have more energy so move around faster and the frequency of their collisions with the walls increases. The particles will hit the walls faster and more often. Therefore the force will be greater and hence the pressure increases.

Question 5

CENTIGRADE =

Answer 5

KELVIN - 273

Question 6

What happens to pressure and temp as temperature of a gas in decreased.

Answer 6

-As the temperature of a gas decreases the energy in the gas falls and the motion of the molecules will slow. Therefore the pressure also falls.
-At a low enough temperature the motion stops and the pressure will be zero.This is called absolute zero and has a value of -273oC.
-This temperature is defined as zero Kelvin.