Hello, would anyone be able to indicate a suitable answer for this question:
'Newtons 3rd law is sometimes stated in the form: "To every action there is an equal and opposite reaction". A student argues that, in that case, the resultant force on an object must always be zero and so it can never be moved. Exlpain what is wrong with the students arguement.'
Thank you very much. Any help appreciated.
The student is applying the 3rd law pair to the same object as the original force.
In fact, the 3rd law pair applies to the object causing the original force on the first object.
imagine kicking a football...
your foot exerts a force on the ball
and, according to newtons third law, the ball exerts a force on your foot
the two forces do not cancel out to give zero because one of the forces is acting on the ball and the other one is acting on your foot.
therefore the resultant force on the ball is NOT zero and it can accelerate.