A ==Key Stage 3=====Meaning===[[Upthrust]] is a [[force]] that acts upwards in a [[fluid]] due to the [[fluid]] being [[Displace|displaced]]. ===About Upthrust===: The [[force]] of [[upthrust]] is equal to the [[weight]] of [[fluid]] that has been [[Displace|displaced]].: An [[object]] in the [[water]] experiences as lot of [[upthrust]] because [[water]] is [[Density|dense]].: [[Upthrust]] is weak in the [[air]] because the [[air]] is not very [[Density|dense]]. For most [[object]]s in [[air]] [[upthrust]] can be ignored because it is so small. ===Examples==={| class="wikitable"|-|[[File:UpthrustBoat.png|center|250px]]|[[File:UpthrustSubmarine.png|center|300px]]|-| style="height:20px; width:300px; text-align:center;" |A boat floats on the water because the [[weight]] is balanced by the [[upthrust]].| style="height:20px; width:300px; text-align:center;" |A submarine can change the amount of [[upthrust]] in order to rise or sink in the [[water]].|}