Pressure and moments

The amount an elastic object stretches is

• the same as the amount of force applied to it

• directly proportional to the amount of force applied to it

Force =

• spring constant x extension

• spring constant ÷ extension

• extension ÷ spring constant

• stretch x extension

The elastic limit is

• where Hooke's law starts to be followed

• the furthest that a material can be stretched

• the furthest that a material can be stretched without being permanently damaged

• when permanent damage happens

Pressure is

• Weight

• force x surface area of object providing the force

• higher if the surface area of an object is larger

• the force exerted over an area

To increase the pressure we put on the ground we could

• Stand on out tiptoes

• Lie down

• Decrease our mass

• Wear shoes with a bigger surface area

Water pressure

• is different in all directions

• increases as you go deeper

• decreases as you go deeper

• only exists in large bodies of water

If an object is less dense that water

• It will sink

• It will float

• It will displace a mass of water that is less than the mass of the object

Density is

• a measure of how compact something is

• Greater in liquids than solids

• calculated by mass x volume

• measured in pascals

If you swing round on one leg of a chair, how much more pressure do you put on one point of the floor than you would if you sat properly?

(a)  

Diving can cause death because of the effects of pressure.

• True

• False