Upthrust: pressure pushes back

5 minAS Level4.3.54.3.6

AI-drafted, independently checked · not yet teacher-reviewed

By the end of this lesson

By the end, you can explain why a fluid pushes upwards on an object and calculate that upthrust using the weight of displaced fluid.

The bottom gets a bigger push

A submerged object has fluid pressing on every side. The fluid pressure is greater lower down, so the upward force on the bottom is greater than the downward force on the top.

Forces on opposite sides balance sideways. The remaining resultant force is upwards: this is upthrust.

Greater pressure at the object's lower face makes the upward force larger than the downward force.

Quick check

Multiple choiceQuestion 1 · Recall

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