forces and matter - topic 14

Question 1

what is pressure

Answer 1

a force exerted normal (90 degrees) to a surface per unit area of that surface

Question 2

pressure =

Answer 2

force / area

Question 3

what is a fluid

Answer 3

a substance that can flow like a gas or liquid

Question 4

the denser the fluid or deeper the point you are looking at

Answer 4

the higher the fluid pressure

Question 5

total pressure at a point in a fluid =

Answer 5

the sum of the pressure due to the fluid itself and surrounding atmospheric pressure

Question 6

the denser the liquid ……

Answer 6

more particles in a given volume and more collisions so higher force exerted so higher pressure

Question 7

as depth increases

Answer 7

number of particles above that point increases and the weight of these particles adds to the pressure experienced

Question 8

liquid pressure =

Answer 8

height x density x gravitational field strength

Question 9

how it atmospheric pressure created

Answer 9

created on a surface by air molecules colliding with the surface

Question 10

as altitude increases,

Answer 10

atmospheric pressure decreases

Question 11

as altitude increases,

Answer 11

atmosphere gets less dense and fewer air molecules that are able to collide with a surface which means lower atmospheric pressure

Question 12

upthrust =

Answer 12

weight of displaced fluid

Question 13

what happens to the force as pressure increases with depth,

Answer 13

force exerted on bottom of object is larger than the force acting on the top of it

Question 14

if upthrust = objects weight

Answer 14

object will float

Question 15

if object weighs more than upthrust

Answer 15

it sinks

Question 16

objects that is more dense than the fluid it is in

Answer 16

is unable to displace enough fluid to equal its weight and will sink as weight is larger than upthrust

Question 17

in order for an object to be stretched, compressed or bend

Answer 17

more than one force needs to be acting on an object in different directions

Question 18

elastically distorted

Answer 18

able to go back to their original shapes and lengths once the force has been removed

Question 19

inelastically distorted

Answer 19

unable to return to their original shapes and lengths once the force has been removed

Question 20

relationship between force and extension

Answer 20

force is directly proportional to extension

Question 21

force =

Answer 21

Spring constant x Extension

Question 22

limit of proportionality

Answer 22

the point beyond which the force applied to an elastic object is no longer directly proportional to the extension of the object

Question 23

elastic limit

Answer 23

the maximum force that can be applied to an object before it is permanently distorted

Question 24

work done

Answer 24

is when a force stretches or compresses an object and causes energy transfer

Question 25

what happens to an objects energy if object is elastically distorted

Answer 25

all energy is transferred to the objects elastic potential store

Question 26

energy transferred in stretching =

Answer 26

0.5 x spring constant x extension^2

Question 27

investigating springs

Answer 27

1. measure natural length of the spring with ruler 2. add mass to spring and allow it to come to rest 3. measure new length and record weight 4. E = 0.5 X k X x^2 5. repeat and plot results graph

Question 28

what is hooke's law

Answer 28

The extension of a spring is directly proportional to the force applied, provided that the limit of proportionality is not exceeded.

Question 29

how is pressure related to force and area

Answer 29

if a person is wearing high heels, their weight(force) acts on the ground over a very small area. This causes a large pressure on the ground.

Question 30

why does atmospheric pressure decrease as height above earth increase

Answer 30

as altitude increases, atmosphere gets less dense which means there are fewer air particles able to collide with a surface so lower atm as altitude increases, there are fewer air particles above a surface so weight above the air decreases