The graph you described is a speed-time plot. If the line is horizontal, that indicates no change in speed over time. In other words, there is no acceleration (acceleration is zero), since there is no change in speed.
Constant speed..
To speed up queries
The line would indicate motion at a constant speed.
constant speed
it depends on what the graph is. if it is a distance vs time graph, the line will be a line with the slope being the speed/total time if it is a speed vs. time graph, the line will be horizontal at y=the speed if it is an acceleration vs time graph, the line will be horizontal at y=0
The graph you described is a speed-time plot. If the line is horizontal, that indicates no change in speed over time. In other words, there is no acceleration (acceleration is zero), since there is no change in speed.
No. It shows zero speed. Velocity is distance/unit time. The slope of the line shows change in distance / change in time. Since distance never changes as time changes, the change in distance is zero. Alternatively, the slope of a horizontal line is zero. If zero speed is considered "constant", then yes, it does show constant speed but the speed is zero.
constant speed
A constant speed.
Acceleration
Constant speed ... zero acceleration.
If a graph shows distance on the vertical axis and time on the horizontal axis, and the speed is steadily increasing, the line representing speed will be a straight line.
The straight horizontal line on the graph says: "Whatever time you look at, the speed is always the same". This is the graph of an object moving with constant speed.
The horizontal speed of the projectile remains constant as there is no force acting in the horizontal direction to change it. Therefore, the horizontal speed of the projectile after 3 seconds will remain at 4 m/s.
Speed
When a body is thrown horizontally with uniform speed, there is no change in the horizontal velocity, so the horizontal component of acceleration is zero. The only acceleration acting on the body is due to gravity in the vertical direction.
that would indicate that the object is at rest (static object) :D