I have a simple mechanics problem (to the left) that can be solved using newton's second law.
Strings are all the same and are light and inextensible and vertical.
When we try finding the tension using these equations:
$3-T=0.3a$ | $T-2=0.2a$
…after solving simultaneously we get that the tension is 2.4 Newtons.
Since the strings are connected to the pulley it's what causes the tension so according to newton's third law it has equal and opposite reaction to the tensions on it. The sum of the tensions is equal to 4.8 and so is the reaction force from the wall.
I'm having trouble with that because I imagine it like the diagram on the right as a combined body having a combined weight and then the tension would be equal to the weight and so…
Can any one help me fix my idea?
Thanks 🙂
Best Answer
On the left, the weights are accelerating.
If you take the asymmetry to its limit, with weights of 5kg and 0kg instead of 3kg and 2kg, then the 5kg weight simply falls with acceleration $g$, and the tension in the string is 0.