Conceptual question on transitional and rotational equilibrium

[xregina12]

3 forces act on an object. If the object is in translational equilibrium, which of the following must be true?
1. the vector sum of the forces =0
2. the magnitude of the 3 forces must be equal
3. the 3 forces must be parallel


would the answer be just 1? I don't think 2 is true because the forces can be unequal but the net force needs to be = 0. And I don't know how what's stated in choice 3 must necessarily contribute to translational equilibirum. Thanks for any imput.

 

[tiny-tim]

Hi xregina12!

3 forces act on an object. If the object is in translational equilibrium, which of the following must be true?
1. the vector sum of the forces =0
2. the magnitude of the 3 forces must be equal
3. the 3 forces must be parallel
…
would the answer be just 1?

Yup!

(Don't worry … you know they put in extra wrong answers just to confuse you )​

 

[thomate1]

You are correct, the answer is only 1. In order for an object to be in translational equilibrium, the vector sum of the forces acting on it must be equal to zero. This means that the forces are balanced and there is no net force acting on the object, causing it to remain at rest or move at a constant velocity. The magnitude of the forces or their direction does not necessarily have to be equal, as long as their vector sum is equal to zero. The forces also do not have to be parallel to each other. However, if the object is also in rotational equilibrium, then the forces must be parallel to each other in order for the object to remain at rest or rotate at a constant speed without any change in its orientation.