You observe three carts moving to the left. Cart A moves to the left at nearly constant speed. Cart B moves to the left, gradually speeding up. Cart C moves to the left, gradually slowing down. Which cart or carts, if any, experience a net force to the left?

The net force, also known as the resultant force, is the sum of all forces acting on an item at the same time.

• Cart 'A' accelerates to the left at a near-constant rate.

• Cart 'B' accelerates as it advances to the left.

• Cart ‘C' moves to the left, swooping down gradually.

• The net force acting on an object moving at constant speed is zero, hence there is no net force acting on cart 'A' toward the left.

• When the item's velocity and force are in the same direction, the object will accelerate.

• Because the Cart B is speeding up and travelling to the left, there is a net force operating on the cart 'B' to the left.

• When the velocity and force directions are opposite, the item slows down.

• Because the cart C is slowing down and travelling to the left, there is a net force operating on the cart 'C' to the right.

Thus, the Cart ‘B’ is the cart that is being pushed to the left by the net force.