P2: Pressure

Question 1

what is pressure

Answer 1

• when particles collide with the sides of the container
• they exert a force at right angles on container

Question 2

how does pressure change in fluid as it gets deeper

Answer 2

• amount of liquid / weight increases
• pressure increases
• the weight depends on the density
• more dens liquid = more pressure exerted

Question 3

pressure to a column of fluid

Answer 3

pressure in coloumn = height x density x gravitational field strength

Question 4

what is upthrust

Answer 4

• partially/totally submerged object
• experience greater pressure on the bottom of surface than top
• creates resultant force up

Question 5

relationship between upthrust and weight of displaced liquid

Answer 5

upthrust = weigjt of displaced liquid

Question 6

what is air pressure

Answer 6

• force per unit excerted by air molecules
• by colliding with surface at right angles

Question 7

what is the atmosphhere

Answer 7

• thin layer of air around earth
• 100km thick

Question 8

how does pressure change with altitude

Answer 8

• higher altitude = lower pressure
• lower weight of particles above + air is less dense
• collide with surfaces less frequenlty

Question 9

atmospheric pressure at sea level

Answer 9

• 14.7 pounds per square inch
• we dont feel it as we are used to it

Question 10

how does increasing temp affect pressure

Answer 10

• increases pressure
• particles have more kinetic energy = move faster
• collide with walls more frequently and with greater force
• greater force over same area = greater pressure

Question 11

how does decreasing the volume affect the pressure

Answer 11

• increases pressure
• less space between particles so collide with walls more frequently
• greater force excerted on the container so increased pressure

Question 12

Boyles law

Answer 12

• pressure and volume are inversly proportional
• in a fixed system

Question 13

how is work done on a gas by compression

Answer 13

• force is used to push piston
• decreases volume of gas
• molecules gain kinetic energy (work is being done –> energy transferred to gas particles)
• move faster = increase in tmep

Question 14

work done by gas

Answer 14

• if gas expands it will do work
• energy transferred from gas
• gas looses energy
• decrease in energy