Taken for a ride!

Vernon Clarke

Teacher - VCE Physics

Why are Luna Park rides so much fun? 

The answer, of course, is that it is all in the physics! 

In particular, most of the fun comes from experiencing different (and changing) g-forces. So what do we  actually mean by g-forces? It is tempting answer this question  by saying that they are ‘gravity forces’. 

Wrong! In fact we will  never (unless we become an astronaut and travel well away from the Earth) experience any changes in the force of gravity on us.  Whatever we do, a constant force of gravity (F = mg) acts on us all the time. And the value of g stays very much the same at 9.8  N/kg. So,g-forces are not the force of gravity on us. 

Well then, what is g force?  g-force is a way to measure rapid acceleration or deceleration commonly experienced by astronauts, pilots, race-car drivers and roller coaster riders. We measure g-force with the unit g, where one g equals the normal pull of gravity on Earth's surface above sea level.

Let’s consider the forces we experience at Luna Park.

At the Luna park the students experience the rides and get a visceral understanding of centripetal acceleration (the acceleration experienced while in uniform circular motion), and the experience of the normal forces as they travel the rollercoaster. They also got to watch an aerobatics display. Then the following week they complete an assessment task where they calculate the forces and speeds involved. Fun calculations!

Images: You can see Jethro pointing out the direction of centripetal acceleration to Aiden on the Supernova! It is a good thing that you can’t hear the screams on the Pharaohs Curse!