NEWTON'S THIRD LAW: ACTION AND REACTION
3 marks · NormalA book rests on a table. The weight of the book is 7 N.
Identify the action force and the reaction force acting on the book and table.
State the direction of each force.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) Action: weight of the book on the table (downwards). Reaction: upward force of the table on the book (upwards).
(b) Action force acts downwards; reaction force acts upwards.
Common mistakes: Describing both forces acting on the same object; Mixing up action and reaction pairs
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Identifies action force as the book pushing down on the table (weight).
B2 (a) · 1 mark · Identifies reaction force as the table pushing up on the book.
B3 (b) · 1 mark · Correctly states directions: down (action), up (reaction).
Worked solution
a) - Action force: The weight of the book acts downwards on the table (book pushes on table). - Reaction force: The upward force from the table acts on the book (table pushes on book). b) - Action force: downwards. - Reaction force: upwards.