Define the term force and give the unit in which force is measured - Leaving Cert Physics - Question 6 - 2006

Being a vector quantity means that force has both magnitude and direction. A force can be fully described by stating how strong it is (magnitude) and the direction it acts in. For example, a force of 10 N directed east is different from a force of 10 N directed west.

1. Mass: The greater the mass of the two bodies, the stronger the gravitational force between them.
2. Distance: The gravitational force decreases as the distance between the two bodies increases, following the inverse square law.

Acceleration due to gravity, denoted as g, is the acceleration experienced by an object due to the gravitational pull of a massive body like the Earth or the Moon. On Earth, g is approximately 9.81 m/s², while on the Moon it is about 1.6 m/s².

The distance fallen, d, is given as 1.6 m and the time, t, is 1.4 s. We can use the second equation of motion: $d = ut + \frac{1}{2}gt^2$ Assuming the initial velocity (u) is 0, the equation simplifies to: $d = \frac{1}{2}gt^2$ Substituting the known values: $1.6 = \frac{1}{2}g(1.4)^2$ Solving for g gives: $g = \frac{1.6 \times 2}{(1.4)^2} \approx 1.6 \text{ m/s}^2$

Weight is calculated using the formula: $W = mg$ Where m is the mass and g is the acceleration due to gravity. For the astronaut: $W = 120 ext{ kg} \times 1.6 ext{ m/s}^2 = 192 ext{ N}$

The astronaut's weight is greater on Earth because the gravitational acceleration (g) on Earth is approximately 9.81 m/s², which is significantly higher than the 1.6 m/s² on the Moon. Since weight is directly proportional to the gravitational acceleration, the astronaut weighs more on Earth.

The Moon does not have a significant atmosphere because its gravitational pull is too weak to retain gases. Lighter gas molecules can escape into space, especially given the Moon's low gravity and lack of substantial geological activity that might otherwise help in holding an atmosphere.