What do you do to investigate the acceleration of an object?

To investigate the acceleration of an object, on a desk draw chalk lines of equal distances e.g. every 10cm. Then on the desk attach a toy car to a string. The string is looped around and pulley and the other end of the spring is attached to a 100g mass. The weight of this mas provides the force acting on the toy car. And a timer is needed. Hold the toy car at the starting point. When ready let go. Because there is a resultant force acting on the string, the car will accelerate along the bench. Record the time taken for the car to pass each distance marker. Although if the car is moving rapidly it would be difficult to record an accurate time. To record the times more accurately record the experiment on a phone, so the experiment can be played back. Then repeat the experiment several times. Each time decrease the weight on the string e.g. 80g, 60g, 40g and 20g.