Q15. Use the example of a lift and satellite in an orbit to mathematically explain the concept of "weightlessness"." (4 Marks)

To explain the concept of "weightlessness" using the example of a lift and a satellite in orbit, we can use the principles of physics and mathematics.<br /><br />Let's consider a satellite in a circular orbit around the Earth. The satellite is moving in a circular path, and it is constantly falling towards the Earth due to the force of gravity. However, the satellite is also moving forward at a high speed, which keeps it from falling directly towards the Earth. This creates a balance between the force of gravity pulling the satellite towards the Earth and the satellite's forward motion.<br /><br />Now, let's consider a person standing inside a lift. The lift is initially at rest, and the person feels their normal weight due to the force of gravity pulling them downwards. However, if the lift suddenly accelerates upwards, the person will feel lighter, and if the lift suddenly accelerates downwards, the person will feel heavier.<br /><br />To mathematically explain the concept of weightlessness, we can use the concept of inertia. Inertia is the tendency of an object to resist changes in its motion. When the satellite is in orbit, it is moving at a constant velocity, and it has a tendency to continue moving in a straight line. However, the force of gravity constantly pulls it towards the Earth, causing it to follow a curved path.<br /><br />The force of gravity acting on the satellite can be calculated using the formula:<br /><br />F = G * (m1 * m2) / r^2<br /><br />where F is the force of gravity, G is the gravitational constant, m1 and m2 are the masses of the two objects (in this case, the satellite and the Earth), and r is the distance between the two objects.<br /><br />The weightlessness experienced by the person in the lift can be explained by the fact that the lift is accelerating downwards, causing the person to feel lighter. The force of gravity acting on the person in the lift can be calculated using the same formula as above, but with the mass of the person instead of the satellite.<br /><br />In summary, weightlessness is the feeling experienced by an object or person when there is no force of gravity acting on them, or when the force of gravity is not sufficient to cause them to feel their normal weight. In the case of the satellite in orbit, it is constantly falling towards the Earth due to the force of gravity, but its forward motion keeps it from falling directly towards the Earth. In the case of the person in the lift, they feel weightless when the lift is accelerating downwards, causing them to feel lighter than their normal weight.