Forces and Pressure Ch3 Flashcards

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1
Q

what is the equation for moment

A

force x distance

around a pivot or folcrum

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2
Q

what are the principles of moment

A
  • if at equilibrium, the moments on both sides of the pivot must be the same
  • if multiple forces are acting, their sum (moment) must be equal if at equilibrium [zero]
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3
Q

how is the centre of gravity influenced

A
  • lowering the centre of mass increases stability
  • wider base increases stability
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4
Q

what are the three types of stability

A

A) stable: requires significant force to shift the centre of mass
B) unstable: requires little force to shift the centre of mass
C) neutral: regardless of the force applied, centre of mass remains at the same point

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5
Q

what does elastic mean

A

an object that if stretched or compressed it will return to its original shape

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6
Q

what does elastic limit mean

A

when a object is stretched or compressed beyond it’s point of return

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7
Q

what is Hooke’s law

A

Hooke identified that there is a proportionality between the extension of a spring and the load

the extension of the spring/ the load of weight = is always the same

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8
Q

what is the equation for spring constant

A

load/ extension

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9
Q

what is pressure

A

pressure is the force applied on an area

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10
Q

what is the equation for pressure

A

force/ area

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11
Q

what are the properties of a liquid pressure

A

A) pressure acts an all directions
B) pressure increases with depth
C) pressure depends on the density of the liquid ie denser=greater pressure
D) pressure doesn’t depend on the shape of the container

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12
Q

what is the equation for pressure in liquids

A

density x gravity x depth

p=pgh

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13
Q

what are the properties of air pressure

A

A) pressure acts on all directions
B) pressure decreases as you rise

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14
Q

what tool do we use to measure atmospheric pressure

A

barometer
altimeter
manometer

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15
Q

how does a barometer work

A

mercury is used beacuse:
- its a liquid, so its non compressible but fills a container
- its a metal, so it has a height density which allows reasonable height changes

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16
Q

what is the unit for a sea level atmosphere

A
  • 760 mmHg
  • 1 atmosphere
  • 100,000 pa pascals
17
Q

what is an altimeter

A

a barometer repurposed to measure altitude

18
Q

what does a manometer measure

A

pressure difference

19
Q

what is the equation for air pressure

A

P1 x V1 = P2 x V2