A 7 kg object undergoes an acceleration of 1.9 m/s2.
(a) What is the magnitude of the resultant force acting on it?
_____ N
(b) If this same force is applied to a 5 kg object, what acceleration is produced?
_____ m/s2

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Do you know what the formula for force is? Once you know that, it is just simple mathematics to find the answer to both parts of the problem.

You will be able to find this formula early in any physics text book.