When does a force happen?

What type of energy is created when you flip the light switch in your room? How does sun's energy come about? What paint color reflect infrared heat best? What is the average constant speed of the object between 2 and 5 seconds? Can you call for a pick up service? The force that pulls on objects and causes acceleration if the objects are not balanced by an opposing force? What month has the greatest current speed? How potential energy arises an elastic spring? What properties do light and waves share? Is fission a particle? What is one positive and one negative thing about nuclear power plant? When interested in examining how one variable changes in relation to another? Do frozen magnets work? Young modulus for spider silk? Did Nikola Tesla have visions or headaches? Does Leuven have a red light district? How do geophones work? What you know about inertia to explain why you feel pressed back into the seat of a car when it accelerates? Why do balloons pop in hot air? Why is a mechanical wave not always produced when a source vibrates?

When does a force happen?