higher physics 2008 q3
DESCRIPTION
Solution to the Higher Physics 2008 paper Q3TRANSCRIPT
Solution
Both boxes are being accelerated forwards by an unbalanced force of 12 N.
First, calculate the acceleration caused by this unbalanced force:
F = ma
12 = 6a you are calculating the acceleration of the whole system i.e. (2 + 4)kg
a = 2 m s-2
Next figure out the unbalanced force that is pulling the 2 kg box forwards, this is the tension between the two boxes:
F = ma
F = 2 x 2 = 4N final answer - B
Note: If you calculate the unbalanced force acting on the 4 kg only then it will be 4 x 2 = 8 N. In other words, the total unbalanced force adds up to the original 12 N given in the question. So in any situation like this, whether it involves two objects or more, calculate the combined acceleration of all the objects first; they are joined together so they will move together with the same acceleration. This value can then be used to calculate the individual tension between each of the joined objects – the sum of which will be the total unbalanced force pulling on the objects.