Question

Can an object have positive acceleration and decreasing speed? No, this is not possible. Yes, speed will always decrease if acceleration is positive. Yes, this is possible if the initial velocity is zero. Yes, this is possible if the initial velocity is negative. Yes, this is possible but only if the object is moving in two dimensions.

Answer 1

Objects can have positive acceleration and decreasing speed when the acceleration is in the opposite direction of the object's velocity, such as a negative velocity paired with positive acceleration.

Step-by-step explanation:

Yes, an object can have positive acceleration and decreasing speed. This scenario occurs when the acceleration vector is opposite to the direction of the velocity vector. To understand this concept, let's assume motion to the right is positive and motion to the left is negative. If an object is moving to the left (negative velocity) and experiences a positive acceleration (such as a force applied to the right), the speed of the object decreases. This is because the acceleration is acting against the direction of the object's motion. This shouldn't be confused with the term 'negative acceleration,' which simply means acceleration in the negative direction in a chosen coordinate system, and does not always signal decreasing speed. Deceleration refers to any acceleration that reduces an object's speed, regardless of direction. Hence, an object with negative velocity and positive acceleration is decelerating, resulting in a decrease in speed.