Here's why:

* Speed times mass equals momentum. Momentum is a measure of an object's mass in motion. It's a vector quantity, meaning it has both magnitude (how much) and direction.

* Force is the rate of change of momentum. This means force is related to how quickly an object's momentum changes.

The correct equation relating force, mass, and acceleration is:

Force (F) = Mass (m) * Acceleration (a)

Where acceleration is the rate of change of velocity.

Therefore, speed times mass is not force, but momentum. To get force, you need to consider the change in momentum over time, which is represented by acceleration.