Yes, a falling apple meets that condition.
Yes. An object moving at constant velocity has zero acceleration. The constant velocity van be any constant including zero velocity. Mathematics acceleration a=dv/dt = 0. Solving this gives v = constant.
Yes, for example, a car moving at constant speed.
A body can have a constant speed yet a nonzero acceleration when it is in a circular motion because though it is having a constant speed but the direction in which it is moving keeps changing at each instance and since acceleration is a vector quantity,it becomes non-zero.
Acceleration is the change in velocity with respect to time. Velocity is the change in position with respect to time (not the change in speed with respect to time, as you have written). Both acceleration and velocity are vector quantities, which means they have both a magnitude and a direction. Speed is simply the magnitude of the velocity. (It's what's called a "scalar" quantity, which is just a number without an associated direction.) An object can have a constant speed, but its direction of motion can be changing over time, so it's velocity is changing. The resulting nonzero change in velocity per unit time is the acceleration. An object need not be moving in a circle to meet these conditions. An object that moves at constant speed, but follows any path that is not a straight line must experience an acceleration. A circular path (like a satellite's orbit) is simply one example example of this.
yes. If the forces acting on the a moving particle are in equilibrium, (e.g. when a spherical object reaches terminal velocity (neglecting increased air resistance as it gets closer to the ground)) then the particle will be moving at a velocity, that is not 0, yet the velocity will remain constant, and the body will not accelerate or decelerate in any direction, and thus the acceleration is 0.
No. A nonzero acceleration means that the velocity is changing, so it can only have a 0 velocity at a single point in time, such as when a ball thrown in the air reaches its peak.
Acceleration is the change in velocity with respect to time. Velocity is the change in position with respect to time (not the change in speed with respect to time, as you have written). Both acceleration and velocity are vector quantities, which means they have both a magnitude and a direction. Speed is simply the magnitude of the velocity. (It's what's called a "scalar" quantity, which is just a number without an associated direction.) An object can have a constant speed, but its direction of motion can be changing over time, so it's velocity is changing. The resulting nonzero change in velocity per unit time is the acceleration. An object need not be moving in a circle to meet these conditions. An object that moves at constant speed, but follows any path that is not a straight line must experience an acceleration. A circular path (like a satellite's orbit) is simply one example example of this.
If an object has zero acceleration, its velocity doesn't have to be zero. Acceleration is a measure of the change in velocity over time. Zero acceleration means there is no change in velocity over time, namely constant velocity. Constant velocity can be any velocity (including zero velocity or "at rest"), so the object's velocity doesn't have to be zero to have zero acceleration.
No because velocity defined as speed in a given direction so if speed is 0 then velocity must also be 0
Yes. As long as the inital and end positions are different, you will have a nonzero average velocity.
Imagine throwing a ball upwards. It slows down(negative acceleration), and is eventually brought to a stop for a moment before starting to accelerate downwards. Keep in mind that throughout the entire journey there is a downward acceleration of g(9.81 m s-2) acting on the ball, even at that moment where the ball stopped mid-air. Of course that condition was only temporary, but it is still possible nonetheless.
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,