ABSTRACT
The ping-pong ball in contrast, with a smaller mass, only needs a smaller force to get it moving. This fits with our everyday experiences in that it is easier to push a car than a lorry to get it moving. The scene has now been set to explore Isaac Newton's powerful idea of gravitation, the idea that explains why apples fall, moons orbit and planets form. Teacher demonstrations like this trigger something that we call situational interest. Situational interest refers to those moments in the classroom where students' interest is generated by some specific object or stimulus. This might include the demonstration. The authors started this chapter with or perhaps showing the video of David Scott, the Apollo 15 astronaut, dropping a falcon feather and a hammer on the Moon and seeing that both objects hit the ground at exactly the same time.
