What is the unit of acceleration in the SI system?

Acceleration is defined as the rate of change of velocity with respect to time. In the International System of Units (SI), velocity is measured in meters per second (m/s). Since acceleration involves a change in velocity over time, it is calculated as the change in velocity divided by the time interval during which that change occurs.

This can be expressed mathematically as:

[ \text{Acceleration} = \frac{\text{Change in Velocity}}{\text{Time}} = \frac{\text{m/s}}{\text{s}} = \text{m/s}^2 ]

This indicates that acceleration measures how many meters per second the velocity of an object changes for each second that passes. Therefore, the unit of acceleration in the SI system is indeed square meters per second, or m/s².

The other options do not represent acceleration correctly. For instance, meters per second (m/s) measures velocity, kilometers per hour (km/h) also measures speed but in a different unit and context, while square meters per second (m²/s) is not a valid unit for acceleration, but rather one that could appear in different contexts such as for certain rates of flux or similar measures.