An object will continue accelerating until

• The resultant force on it begins to decrease
• The velocity changes direction
• The resultant force on it is zero
• The resultant force is at right angles to its direction of motion

Acceleration of an object is influenced by the net force acting on it. Here’s a breakdown of the options provided:

Key Factors Affecting Acceleration

• The resultant force on it begins to decrease: If the net force acting on the object decreases, its acceleration will also decrease.
• The velocity changes direction: Changing direction can involve acceleration, but it doesn't necessarily mean the object will stop accelerating.
• The resultant force on it is zero: When the net force is zero, the object will stop accelerating and maintain a constant velocity.
• The resultant force is at right angles to its direction of motion: This can cause the object to change direction without changing speed, such as in circular motion.

In summary, an object will continue to accelerate until the resultant force acting on it is zero. This means that the correct answer is:

The resultant force on it is zero