Lesson 11 of 15
The push a liquid gives
Show on a big screenPush a plastic ball under water, then release it. It rises fast. What pushes it?
Step 1 of 4
- A ball is pushed under water.
- The Earth pulls it down. That is its weight.
- The water pushes it up. That is upthrust. Here it is bigger than the weight.
- Weight bigger: it sinks. Both the same: it floats. Upthrust bigger: it is pushed up.
The water pushes it up. This push is called .
New word
- Upthrust — the upward push a liquid gives an object in it. It is also called buoyant force.
The rule
A liquid pushes up on an object. This push is . Weight bigger than upthrust: the object sinks. Both the same: it floats.
bigger than weight: the object is pushed up.
Compare the two numbers. Pick what happens.
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Try the lab to finish this lesson.