Content Focus

We will explore and solve problems of objects moving in projectile motion, circular motion and orbital motion due to the pull of gravity.

"Motion in one dimension at constant velocity or constant acceleration can be explained and analysed relatively simply. However, motion is frequently more complicated because objects move in two or three dimensions, causing the net force to vary in size or direction.

"Students develop an understanding that all forms of complex motion can be understood by analysing the forces acting on a system, including the energy transformations taking place within and around the system. By applying new mathematical techniques, students model and predict the motion of objects within systems. They examine two-dimensional motion, including projectile motion and uniform circular motion, along with the orbital motion of planets and satellites, which are modelled as an approximation to uniform circular motion."

NSW Education Standards Authority (NESA) (2017), Physics Stage 6 Syllabus, p. 52.

Biblical Perspective

"The story goes that Isaac Newton was taking tea under an apple tree one sunny afternoon when an apple dislodged itself and landed on his head. It dawned on Newton that what goes up must come down, and this formed the basis of his Universal Law of Gravity. A tale perhaps, but there is evidence in writings at that time to suggest it actually happened. " ("Sir ISAAC NEWTON" in CORDIS, 2 October 2002, internet <http://cordis.europa.eu/scienceweek/inspiration01.htm>, accessed 27 September 2017)

What does the Bible say about projectile motion? King Ahaziah sent his captain up the mountain to say to Elijah to come down (2 Kings 1:9), but this is incidental and descriptive, rather than explaining the physics of gravity! Similarly, the wind in a storm "lifts up the waves of the sea," which then "go down again to the depths" (Psalm 107:25-26). King David knew the presence and omniscience of the Lord, and sang to God, "You know my sitting down and my rising up" (Psalm 139:2). Indeed, he later affirmed that "The Lord upholds all who fall" (Psalm 145:14). Jonah said to the sailors in his ship, "Pick me up and throw me [down] into the sea," due to his running away from God, "So they picked up Jonah and threw him [down] into the sea" (Jonah 1:12, 15). He most probably followed a projectile motion!

More importantly, God created gravity to hold the stars, planets and natural satellites (moons) in place (Genesis 1:16). He continues to sustain all things in the universe, as Paul wrote about Christ in Colossians 1:16-17: "For by Him all things were created that are in heaven and that are on earth, visible and invisible [including gravity] ... All things were created through Him and for Him. And He is before all things, and in Him all things consist."

For a Biblical Perspective of Electromagnetism, click here.

Inquiry Questions

Projectile Motion

How can models that are used to explain projectile motion be used to analyse and make predictions?

Circular Motion

Why do objects move in circles?

Motion in Gravitational Fields

How does the force of gravity determine the motion of planets and satellites?