Work Done and Forces
Work happens whenever you apply a force to move something - whether it's pushing a trolley or lifting a book. The key thing to remember is that both force AND movement must occur for work to be done.
Forces come in two main types that affect our daily lives. Contact forces occur when surfaces touch, like friction when you rub your hands together. Non-contact forces work from a distance - think about how magnets attract metal or how gravity pulls objects downward.
Weight and mass often confuse students, but they're quite different. Your mass (measured in kg) stays the same whether you're on Earth or the Moon - it's simply how much matter you contain. Your weight (measured in Newtons) is actually a force created by gravity pulling on your mass.
💡 Quick Check: Your mass is 60kg everywhere in the universe, but your weight changes depending on the planet you're on!
The formula W = mg helps you calculate weight, where 'g' represents Earth's gravitational field strength (approximately 10 N/kg). Gravitational potential energy (GPE) stores energy in objects based on their height - this explains why a book on a high shelf has more stored energy than one on the floor.
