Question

which of the following shows an example of an unbalanced force? a train moving at a constant speed. a person sitting in a chair. a student knocking over a soda. a pencil lying on a desk.

Explanation:

• For a train moving at a constant speed, the forces (like the forward - pulling force and the frictional force) are balanced.
• When a person is sitting in a chair, the gravitational force (pulling down) and the normal force (chair pushing up) are balanced.
• When a pencil is lying on a desk, the gravitational force and the normal force from the desk are balanced.
• When a student knocks over a soda, an unbalanced force (the force applied by the student) acts on the soda, causing it to change its state of motion.

Answer:

C. A student knocking over a soda.