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

As a vector quantity, force has both magnitude and direction. This means that the effect of a force depends not only on how strong it is but also on the direction in which it acts. For example, pushing a box with a force of 10 N to the right is different from pushing it with the same force to the left.

1. Mass: The greater the mass of either body, the greater the gravitational force between them.
2. Distance: The gravitational force decreases as the distance between the centers of the two bodies increases.

Acceleration due to gravity, g, is the acceleration experienced by an object when it is in free fall due to the gravitational pull of a celestial body, such as the Earth or the Moon. It is a constant value, with g on Earth being approximately 9.8 m/s².

To find the acceleration due to gravity, we can use the formula for distance, which is given by:

$s = ut + \frac{1}{2} a t^2$

Here, s = 1.6 m, u = 0 (initial velocity), and t = 1.4 s. Plugging in the known values:

$1.6 = 0 \cdot 1.4 + \frac{1}{2} a (1.4)^2$

This simplifies to:

$1.6 = \frac{1}{2} a \cdot 1.96$

Rearranging gives:

$a = \frac{1.6 \cdot 2}{1.96} = 1.63 \text{ m/s}^2$

Hence, the acceleration due to gravity on the moon is approximately 1.6 m/s².

Weight is calculated using the formula:

$W = mg$

where m is mass and g is the acceleration due to gravity. On the moon, utilizing g = 1.6 m/s²:

$W = 120 ext{ kg} \cdot 1.6 ext{ m/s}^2 = 192 ext{ N}$

Thus, the astronaut’s weight on the moon is 192 Newtons.

The astronaut's weight is greater on Earth because the acceleration due to gravity is significantly higher on Earth (approximately 9.8 m/s²) compared to the Moon (1.6 m/s²). Since weight depends on mass and the force of gravity acting on that mass, a higher gravitational force results in a greater weight.

The Moon does not have a significant atmosphere because its gravitational force is not strong enough to retain gases. With a weaker gravitational pull, any gases that might have formed or been released would escape into space, resulting in the Moon having no atmosphere.