Define the term force and state the unit of force - Leaving Cert Physics - Question 6 - 2016

Another example of a vector quantity is velocity, which also has both magnitude and direction.

The size of the gravitational force between two bodies is affected by the following factors:

1. The mass of the first body.
2. The mass of the second body.
3. The distance between the centers of the two bodies.

Using the formula $g = \frac{GM}{r^2}$ where:

• $G = 6.67 \times 10^{-11} \; \text{N m}^2/\text{kg}^2$
• $M = 1.3 \times 10^{26} \; \text{kg}$
• $r = 1186 \; \text{km} = 1.186 \times 10^{6} \; \text{m}$, we can calculate:

$g = \frac{(6.67 \times 10^{-11}) (1.3 \times 10^{26})}{(1.186 \times 10^{6})^2} \approx 0.62 \; \text{m/s}^2$

Weight can be calculated using the formula: $\text{Weight} = m \times g$ where:

• $m = 450 \; \text{kg}$ (mass of the spacecraft)
• $g = 0.62 \; \text{m/s}^2$ (acceleration due to gravity on Pluto)

Thus, $\text{Weight} = 450 \times 0.62 = 279 \; \text{N}$

I would expect its weight to be less than it would be at the surface. This is because the gravitational force decreases with distance from the center of the planet. As the spacecraft is 1000 km from the surface, it is effectively further away, resulting in a smaller gravitational pull compared to when it is on the surface.

Pluto's atmosphere exerts very low pressure because it is composed primarily of nitrogen, which is extremely thin. The atmospheric density is low due to its small mass and the fact that Pluto is far from the sun, resulting in very cold temperatures that cause most gases to freeze and diminish the atmosphere.

Solar panels were unsuitable for the New Horizons mission because Pluto is very far from the sun. At such a distance, solar energy is significantly weaker, which would not generate enough power to operate the spacecraft’s instruments effectively.