Answer:
AD
Step-by-step explanation:
A motion diagram is used to represent the motion of an object. Each point represents the location of the object after equal intervals of time, and the velocity of the object is represented using arrows.
The motion diagram for this problem has been attached here. The question is asking us to analyze the motion at point A. We can make the following observations for the motion diagram at point A:
- The direction of the arrows does not change --> this means that the object is moving on a straight line
- The length of the arrows remains constant at A --> this means that the object is moving at constant speed
Of all the situations listed in the question, only two of them are compatible with these observations:
A) A car is moving along a straight road at a constant speed.
D) A hockey puck slides along a horizontal icy (frictionless) surface. (Frictionless surface means there is no friction acting on the puck, so the acceleration is zero and therefore the speed is constant).
All the other options involves a non-zero acceleration, so that the velocity is not constant. Therefore, only A and D are the correct options.