The trolley is 5 m long and rests on smooth rails. At opposite ends of the cart are two boys.

The trolley is 5 m long and rests on smooth rails. At opposite ends of the cart are two boys. The weight of the cart is 75 kg, the weight of the boys is 45 kg and 30 kg. The boys switch places. How many centimeters will the cart move?

If both boys weighed 30 kg, then the center of gravity of the cart would be in the middle of it. Consequently, the displacement of the center of gravity relative to the middle is determined only by the “extra” 15 kg, which have moved from one edge to the other.

In one position, the center of gravity of the entire system is located at the point 15kg * 2.5m / 150kg = 25cm, in the other -25cm. The center of gravity of the entire system must remain in place when moving.

Answer: The cart will move 50 cm.