Difference between revisions of "Upthrust"
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===Example Calculations=== | ===Example Calculations=== | ||
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| + | | style="height:20px; width:200px; text-align:center;" |A cube of 1m sides is submersed in [[water]] which has a [[density]] of 1000kg/m3 on [[Earth]] with a [[Gravitational Field Strength|gravitational field strength]] of 9.8N/kg. | ||
| + | | style="height:20px; width:200px; text-align:center;" |A cube of 20m sides is submersed in [[water]] which has a [[density]] of 1000kg/m3 on [[Earth]] with a [[Gravitational Field Strength|gravitational field strength]] of 9.8N/kg. | ||
| + | | style="height:20px; width:200px; text-align:center;" |A cube of 4m sides is submersed in [[water]] which has a [[density]] of 1000kg/m3 on [[Earth]] with a [[Gravitational Field Strength|gravitational field strength]] of 9.8N/kg. | ||
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===Examples=== | ===Examples=== | ||
Revision as of 11:18, 11 February 2019
Contents
Key Stage 3
Meaning
Upthrust is a force that acts upwards in a fluid due to the fluid being displaced.
About Upthrust
- Upthrust is a force so it is measured in Newtons.
- The force of upthrust is equal to the weight of fluid that has been displaced by an object.
- An object in the water experiences more upthrust than an object in air because water is more dense than air.
- Upthrust is weak in the air because the air is not very dense. For most objects in air upthrust can be ignored because it is so small.
- Upthrust is caused by the pressure in a fluid. Pressure increases with depth so the bottom of an object will experience more pressure than the top. This difference in pressure results in a difference between the force on the bottom and the top, known as upthrust.
Examples
 |
 |
| A boat floats on the water because the weight is balanced by the upthrust. | A submarine can change the amount of upthrust in order to rise or sink in the water. |
Key Stage 4 Foundation
Meaning
Upthrust is a force that acts upwards in a fluid due to the fluid being displaced.
About Upthrust
- Upthrust is a force so it is measured in Newtons.
- The force of upthrust is equal to the weight of fluid that has been displaced by an object.
- An object in the water experiences more upthrust than an object in air because water is more dense than air.
- Upthrust is weak in the air because the air is not very dense. For most objects in air upthrust can be ignored because it is so small.
- Upthrust is caused by the pressure in a fluid. Pressure increases with depth so the bottom of an object will experience more pressure than the top. This difference in pressure results in a difference between the force on the bottom and the top, known as upthrust.
Key Stage 4 Higher
Calculating Upthrust
NB: You don not need to remember this equation.
Upthrust = (Density of the fluid) x (Gravitational Field Strength) x (Object Height) x (Cross sectional area perpendicular to the height)
\( F_U = \rho g h A\)
Where\[ F_U\] = Force of upthrust.
\(g\) = Gravitational Field Strength
\(h\) = Height of object from top to bottom.
\(A\) = Cross sectional area of the object perpendicular to the height.
Example Calculations
 |
 |
 |
| A cube of 1m sides is submersed in water which has a density of 1000kg/m3 on Earth with a gravitational field strength of 9.8N/kg. | A cube of 20m sides is submersed in water which has a density of 1000kg/m3 on Earth with a gravitational field strength of 9.8N/kg. | A cube of 4m sides is submersed in water which has a density of 1000kg/m3 on Earth with a gravitational field strength of 9.8N/kg. |
Examples
|
|
| A boat floats on the water because the weight is balanced by the upthrust. | A submarine can change the amount of upthrust in order to rise or sink in the water. |