Acar, starting from the origin, travels
4 km east and thea 7 km west what is
the net displacement of the car from
the initial point?

The net displacement of the car is 3 km West

Explanation:

Please see the attached drawing to understand the car's trajectory: First in the East direction for 4 km (indicated by the green arrow that starts at the origin (zero), and stops at position 4 on the right (East).

Then from that position, it moves back towards the West going over its initial path, it goes through the origin and continues for 3 more km completing a moving to the West a total of 7 km. This is indicated in the drawing with an orange trace that end in position 3 to the left (West) of zero.

So, its NET displacement considered from the point of departure (origin at zero) to the final point where the trip ended, is 3 km to the west.

The net displacement of the car from the initial point will be 3 kilometer west.

Explanation:

Displacement is the shortest distance between two points, whereas the distance is the total distance between two points.

Displacement is a vector quantity and distance is scalar quantity. Let the car starts from point A and reaches point B in the East direction, i.e., 4 km.

Now from point B it starts moving west and reaches point C beyond point A, i.e., 7 km.  

                                                A.>B    4KM

                    C <B     7KM

finally the resultant distance is 3 km west

what was the acceleration of the 2 kg cart?

⇒ 16.0 cm/s2

what was the acceleration of the 4 kg cart?

⇒ 8.1 cm/s2

what was the acceleration of the 6 kg cart?

⇒ 5.3 cm/s2

this is a good question! i'll do some research and come back when i have the answer!