Definition: When the speed of an object remains the same – it does not increase or decrease – we say it is moving at a constant speed.

Speed is the rate of change of distance(basically how much distance(m) has been covered in a particular time(s)). Velocity is the rate of change of displacement( change of distance in a particular direction with respect to time) , and acceleration is the rate of change of velocity per unit of time.

Speed and velocity both represent a way to measure the change in position of an object relative to time. In fact, for a straight line motion, the speed and velocity of an object are the same (since distance and displacement will be the same). Speed and velocity are measured in the same units: meters per second or m/s.

1. Fingerspell.
2. constant speed.

Constant speed does not mean acceleration. Acceleration is the variation of speed over time, or dV/dt. At constant speed, acceleration is zero, no doubt. The component of acceleration along the direction of motion changes the speed.

An object which experiences either a change in the magnitude or the direction of the velocity vector can be said to be accelerating. A change in direction constitutes a velocity change and therefore an acceleration.

Yes, an object can have zero velocity and still be accelerating simultaneously.

This acceleration is the gravitational acceleration. At that point the component of acceleration/gravitational acceleration works there. So, at the topmost point the velocity is zero but acceleration is not and has a finite value. Therefore, a body can have zero velocity and finite acceleration.

Yes, it’s possible to have zero speed while accelerating, but only for an instant. Acceleration is the rate at which an object’s speed and direction are changing with time, so whenever an object passes through zero speed as it reverses directions it has a non-zero acceleration but a speed of zero.

No. It is not possible for an object to have 0 speed but non-zero velocity. It is because in a straight line motion when the magnitude of speed is zero, then with or without considering its direction , velocity will be zero only.

Acceleration is the change in velocity, so when you say that the acceleration reverses in direction, it means that the object is transferring from either speeding up to slowing down, like a skateboard which just passed the bottom of a U-shaped ramp, or from slowing down to speeding up.

Negative Acceleration. Deceleration always refers to acceleration in the direction opposite to the direction of the velocity. Deceleration always reduces speed. Negative acceleration, however, is acceleration in the negative direction in the chosen coordinate system.

Acceleration and deceleration are terms which are generally considered to have opposite meaning. In literal sense, acceleration is considered to describe an increase or positive change of speed or velocity. On the other hand, deceleration is considered to describe a decrease or negative change of speed or velocity.