Here's how acceleration works:
* Positive acceleration: Indicates that the velocity is increasing in the positive direction (e.g., a car speeding up to the right).
* Negative acceleration: Indicates that the velocity is decreasing in the positive direction (e.g., a car slowing down to the right) or increasing in the negative direction (e.g., a car speeding up to the left).
The general formula for acceleration is:
a = (v_f - v_i) / t
Where:
* a is acceleration
* v_f is the final velocity
* v_i is the initial velocity
* t is the time interval
To determine if the acceleration is positive or negative, you need to consider the direction of the velocity change:
* Positive acceleration: If the final velocity is greater than the initial velocity, the acceleration is positive.
* Negative acceleration: If the final velocity is less than the initial velocity, the acceleration is negative.
Example:
* A car starts from rest (v_i = 0 m/s) and accelerates to 20 m/s in 5 seconds.
* a = (20 m/s - 0 m/s) / 5 s = 4 m/s²
* Since the final velocity is greater than the initial velocity, the acceleration is positive. This means the car is speeding up.
Key takeaway: Positive or negative acceleration depends on the direction of velocity change, not on a separate formula. You determine the sign of acceleration based on how the velocity is changing.
