When an objects acceleration is 0 at an instant t in time, its velocity is
1. zero at t.
2. negative at t.
3. positive at t.
4. not changing at t.
My teacher never taught us this, can someone help me figure it out?
Acceleration is the rate of change of velocity, that means, it tells you how fast the velocity is changing.
If acceleration is zero, this means that velocity is not changing at all. Hence, velocity is not changing at t.