Short Answer 
The car travels at a constant velocity with no acceleration when moving right. Pressing the accelerator causes both velocity and acceleration to point right, leading to an increase in speed. Engaging the brakes changes the acceleration direction to left, causing the car to decelerate while maintaining its rightward velocity.
Step 1: Understanding Constant Velocity
When a car is traveling at a constant velocity, it means that its speed and direction are unchanged. In this case, the car is moving from left to right. The velocity vector, which indicates the direction of the car’s movement, will point to the right. This means there is no acceleration acting on the car at this moment.
Step 2: Applying the Accelerator
If the driver pushes down on the accelerator, the car will begin to accelerate. In this scenario, both the velocity and the acceleration vectors will point in the same direction, which is to the right. This is because the car is gaining speed in the direction it is already going. The relationship between acceleration and velocity is crucial in determining how the car will move.
Step 3: Engaging the Brakes
When the driver subsequently pushes down on the brakes, a significant change occurs. The car will still have its velocity vector pointing to the right, but the acceleration vector will now point to the left, which means the car is decelerating. This change reflects an increase in the opposition to the car’s motion, effectively reducing its speed.