Two forces of equal magnitude act on the same object. Which of the following must be true?
a. The object is moving.
b. The object is accelerating.
c. If the object is initially at rest, it cannot remain at rest.
d. The two forces form a third-law pair.
e. None of the above.
e. None of the above.
To determine which of the options must be true, we need to analyze the given information.
When two forces of equal magnitude act on an object, there are several possibilities:
1. If the object is at rest:
- The forces are acting in opposite directions, canceling each other out.
- The net force on the object is zero, and according to Newton's First Law, the object will remain at rest unless acted upon by an external force.
Therefore, option (c) is not necessarily true. The object can remain at rest if the two forces cancel each other out completely.
2. If the object is moving at a constant velocity:
- The forces are acting in opposite directions but are not canceling each other out completely.
- The net force on the object is still zero, as the forces are equal and opposite.
In this case, the object is not accelerating, so option (b) is not necessarily true.
3. If the object is accelerating:
- The forces are acting in opposite directions, but one force is greater than the other.
- The net force on the object is not zero, leading to acceleration.
In this case, the object is accelerating, so option (b) could be true.
4. Regarding option (a):
- Whether the object is moving or not depends on the initial conditions and forces acting on the object.
- If the object is already in motion, the forces may affect its motion, but it does not necessarily mean the object is moving.
Therefore, option (a) is not necessarily true.
5. Regarding option (d):
- The two forces being equal in magnitude does not necessarily mean they form a third-law pair.
- Third-law pairs involve interactions between different objects, and these forces seem to be acting on the same object.
Therefore, option (d) is not necessarily true.
Given these considerations, the correct answer is option (e): None of the above.