An astronaut standing on Earth could easily lift a wrench having a mass of \(1 \mathrm{kg}\), but not a scientific instrument with a mass of \(100 \mathrm{kg}\). In the International Space Station, she is quite capable of manipulating both, although the scientific instrument responds much more slowly than the wrench. Explain why the scientific instrument responds more slowly.

Microgravity refers to the condition where objects appear to be weightless and the effects of gravity are significantly weaker than on Earth. Inside the International Space Station (ISS), astronauts experience microgravity due to the station's continuous free fall as it orbits the Earth. Although gravity is still present, it is so minimal that it feels almost nonexistent.

In this unique environment, objects do not fall to the ground as they do on Earth. This allows astronauts to easily manipulate items regardless of their mass. However, the objects still retain their inertia, meaning heavier objects resist changes in motion more than lighter ones.

Understanding microgravity is crucial because it helps explain why astronauts can manage heavy objects in space but still find them difficult to control compared to lighter objects.

Mass is the amount of matter in an object, and it remains constant regardless of the object's location. It's important to note that mass differs from weight. While weight is dependent on gravity and can vary based on where the object is, mass is an intrinsic property.

An object with a higher mass (such as the 100 kg scientific instrument) has more inertia, which is its resistance to changes in motion. This resistance is present regardless of whether the object is on Earth or in microgravity. In the International Space Station, since gravity is negligible, the astronaut does not have to grapple with the weight of the instrument. However, she still has to deal with its mass, which affects how quickly or slowly it responds to her efforts to move it.

Therefore, while mass doesn’t change in microgravity, the effects of inertia become more noticeable. This is why the scientific instrument responds more slowly than the wrench.

Newton's First Law, often referred to as the law of inertia, states that an object at rest remains at rest, and an object in motion remains in motion at a constant velocity unless acted upon by an external force. This fundamental principle of physics explains why objects with more mass (and thus more inertia) resist changes in their motion more than lighter objects.

On Earth, gravity is the primary external force acting on objects, which affects how we perceive and interact with them. In the ISS, gravity's influence is minimal, so astronauts primarily deal with inertia. When an astronaut pushes or pulls a 100 kg scientific instrument, the instrument's mass and inertia resist the change in motion more than a 1 kg wrench. This resistance explains why the instrument moves more slowly in response to the astronaut's efforts.

Understanding Newton's First Law is key to grasping why heavy masses are difficult to handle even in microgravity. It also highlights the importance of forces required to initiate or stop the motion of different objects.