Zero.
For motion at constant speed along a straight line, the acceleration is zero.
The line would indicate motion at a constant speed.
Straight up in the air. It's already moving at your speed, so it's horizontal velocity will remain constant. Vertical motion and horizontal motion don't affect each other.
Horizontal motion refers to movement along the x-axis, while vertical motion refers to movement along the y-axis. In horizontal motion, the speed and acceleration are typically constant, while in vertical motion, the influence of gravity causes changes in speed and acceleration. Both types of motion can occur simultaneously in two-dimensional motion.
The ball would continue to move at the same speed as the train in the horizontal direction, but its vertical speed would be affected by gravity. The overall motion of the ball would be a combination of the horizontal motion at the speed of the train and the vertical motion due to gravity.
Assuming it is a spped v/s time graph, a horizontal line represents motion at a constant speed.
The straight horizontal line would indicate constant speed.(NOT constant velocity. The velocity could very well be changing, but the graphdoesn't tell you anything about the direction of the motion, only that the speedis constant.)
The shape of the speed-time graph for an object moving with variable speed would depend on how its speed changes over time. It could be linear if the speed changes at a constant rate (acceleration or deceleration), curved if the acceleration is not constant, or a combination of different shapes if the speed fluctuates.
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.
constant speed
A constant speed.
Acceleration