Final answer:
When an object speeds up, it experiences positive acceleration, indicating that the direction of acceleration and velocity are the same, resulting in an increase in speed. Option 1 is correct.
Step-by-step explanation:
What kind of acceleration occurs when an object speeds up? The correct answer is positive acceleration. This is when the acceleration vector points in the same direction as the velocity vector of the object, causing an increase in the object's speed.
Acceleration in physics is a vector quantity, meaning it has both magnitude and direction, and doesn't provide information about the motion itself but rather how the motion is changing. If both the velocity and acceleration are in the same direction, the object will speed up, whether the direction is taken as positive or negative in the coordinate system. A positive acceleration implies increasing speed in the chosen positive direction of the coordinate system. Conversely, positive or negative acceleration that is opposite to the direction of motion causes the object to slow down or decelerate.
For example, let's say a car is moving to the right and speeding up. According to our coordinate system, where the right direction is considered positive, the car has positive acceleration. On the other hand, if the car was moving to the left and also speeding up, this would be described as negative acceleration due to our coordinate system, but since the car's speed is increasing, it is still considered to be accelerating.