**Correct Option: C. A passenger in a bus lurches forward when the bus suddenly stops.** ### Explanation of the Correct Answer **Understanding Inertia and Newton's First Law of Motion:** Inertia is the tendency of an object to resist changes in its state of motion. Newton's First Law of Motion states that an object at rest will remain at rest, and an object in motion will continue in motion with the same speed and in the same direction unless acted upon by a net external force. This means that if no force is acting on an object, it will not change its state of motion. **Scenario C Explained:** In the scenario where a passenger in a bus lurches forward when the bus suddenly stops, we can see inertia in action. When the bus is moving, both the bus and the passenger are in motion. When the bus suddenly stops, the bus experiences a force (the brakes) that changes its state of motion. However, the passenger's body, due to inertia, wants to continue moving forward at the same speed the bus was traveling. Since there is no force acting on the passenger to stop them immediately (the seatbelt or the seat itself may provide some resistance, but it is not enough to counteract the forward motion), the passenger lurches forward. This illustrates inertia perfectly: the passenger's body continues in motion while the bus stops. ### Why the Other Options Are Incorrect **Option A: A book sliding off a table comes to a stop on the floor due to friction.** - This scenario does not illustrate inertia effectively because it involves an external force (friction) acting on the book. The book does not continue moving indefinitely; instead, it stops due to the frictional force between the book and the floor. This contradicts the idea of inertia, which is about maintaining motion in the absence of external forces. **Option B: A car accelerates as the driver presses the gas pedal.** - This scenario describes a change in motion due to an applied force (the driver pressing the gas pedal). While it involves motion, it does not illustrate inertia because the car is not maintaining its state of motion; it is changing its state (accelerating) due to the force applied. Inertia is about resisting changes in motion, not about initiating them. **Option D: A ball thrown into the air eventually falls back down due to gravity.** - While this scenario involves motion and the effects of gravity, it does not illustrate inertia in the context of Newton's First Law. The ball's upward motion is eventually halted by gravity, which is an external force acting on it. The ball does not continue moving upward indefinitely; it changes its state of motion due to the gravitational force acting on it. ### Summary of Key Points - **Inertia** is the resistance of an object to change its state of motion. - **Newton's First Law** states that an object will remain at rest or in uniform motion unless acted upon by an external force. - **Correct Scenario (C)** illustrates inertia as the passenger continues moving forward when the bus stops, demonstrating the effect of inertia. - **Incorrect Scenarios (A, B, D)** involve external forces that change the state of motion, thus not illustrating the concept of inertia effectively. ### Revision Summary - Inertia is the tendency of an object to resist changes in motion. - Newton's First Law states that objects remain in their state of motion unless acted upon by an external force. - The best illustration of inertia is when a passenger lurches forward in a stopping bus (Option C). - Other options involve external forces that change motion, failing to demonstrate inertia.