Yes, when it comes back to the starting point.
Since speed is a scalar quantity, the only way the average speed can be zero is if the instantaneous speed is at all times zero, making it not a moving body, so no on the average speed. The average velocity, on the other hand, can easily be zero. The simplest example is you running in a circle.
Yes, when it comes back to the starting point.
The instantaneous speed is the speed of a moving body at an instant. Average speed is the overall speed through a period of time. These are two important aspects of differentiation in calculus.
An object moving in a circular path at constant speed will have a non-zero average speed and zero average velocity since velocity is a vector parameter,
The velocity changes. called acceleration.
If a body is moving with variable speed, then the only thing you can say aboutits speed/time graph is that the graph is not a straight, horizontal line.
no it cannot be zero as the formula for average speed is total distance/total time . if we will come back to the starting point also then also there is distance covered . so it cannot be zero.
It doesn't
"velocity"
If the net force on a body is zero, then the body will not accelerate ... its speed and direction of motion won't change. If it was moving a second ago, then it will continue moving at the same speed and in the same direction. If it was not moving a second ago, it won't start moving.
Speed = Distance/Time
Yes; for example, an object moving in a circle.