Question: 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 available forces acting on an item at the same time. The net forces can be expressed in terms of Newton.

• 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 a particular 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 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 Cart 'C' to the right.

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