Mass is a measure of the amount of matter in an object, while inertia is the tendency of an object to resist changes in its state of motion. In other words, an object with more mass has more inertia, which means it is harder to move or stop. For example, consider a baseball and a basketball. The baseball has a smaller mass than the basketball, which means it has less inertia. Therefore, it is easier to throw the baseball or stop it if it is moving, compared to the basketball. Similarly, a truck with a larger mass has more inertia than a bicycle with a smaller mass, which means it is harder to accelerate or stop the truck compared to the bicycle. Another example of the relationship between mass and inertia is in space travel. Spacecraft are designed to be as lightweight as possible, because they need to accelerate and decelerate with limited fuel. However, the astronauts inside the spacecraft still have mass, which means they have inertia. This can be seen when a spacecraft changes course or slows down, causing the astronauts to experience a force that pulls them in a different direction.