Practice question · Multiple choice
A book sits on a table. The table pushes up on the book with exactly the book's weight. Is that Newton's third law?
Hints
- Third-law pairs act on two DIFFERENT objects. Which object do these two forces act on?
- Name the partner of 'table pushes book up'. What is it acting on?
Show the answer
B. No, these act on the same object and balance under the first law
Why
Both forces act on the book, so they are a first-law balance, not a third-law pair, the partner of the table's push is the book pushing down on the table. It is the commonest third-law error, and the test is always the same: name the two objects and check they differ.
Practise Newton's Laws and Dynamics
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