A and B are placed on a smooth horizontal plane and connected by light spring A and B are placed on a smooth horizontal plane and connected by a light spring. Now, the opposite horizontal forces F1 and F2 are applied to a and B respectively, and F1 = 20n and F2 = 10N Spring force If there is only F1, what is the spring force?

A and B are placed on a smooth horizontal plane and connected by light spring A and B are placed on a smooth horizontal plane and connected by a light spring. Now, the opposite horizontal forces F1 and F2 are applied to a and B respectively, and F1 = 20n and F2 = 10N Spring force If there is only F1, what is the spring force?

First look at the whole, the total mass is 5, the total force is 10, the direction is left, so the acceleration is 2, the direction is left
Then study two objects separately, such as a, the external force is 2 * 2 = 4 direction left, so the elastic force is 20-4 = 16 direction right
This step can also be done by b-analysis
For F1 only, the acceleration is 4 to the left
Using B to analyze, the combined external force is 4 * 3 = 12, which is the elastic force
Note: all are calculated under the international system of units
The direction of the force is unknown, but it does not affect the final result. It may affect the direction of motion and elasticity