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## The Force of Tension Tension force and horizontal pulling forces. How Newton’s Laws of Motion can explain the force of tension; how tension remains constant when the forces pulling on a rope from opposite ends and in opposite directions become unbalanced; tension and vertical pulling forces ; explanation of tension in a cable which is attached a light to a ceiling; tension in the cable of an escalator; tension at the molecular level. ## Friction and Forward Motion In this article we investigate the force of friction which opposes the forward motion of objects; we look at the force that needs to be applied to an object before friction can be overcome and forward motion can occur. We explain static and kinetic friction, how friction comes in pairs and represents the interaction between two different surfaces; what happens when a surface is frictionless, how friction can help or harm. ## Freefall and Aerodynamic Drag Early theories about the motion of falling objects; characteristics of objects in freefall; how the shape,cross sectional area and mass of different objects affect the speed of objects in freefall; the hammer and feather experiment as carried out on the Moon in 1971; two different types of freefall ; Felix Baumgartner’s incredible jump from the edge of space; reaching terminal velocity. ## Forces of Drag-What are they? This article investigates the three main forces of drag- namely aerodynamic drag, hydrodynamic drag and frictional drag (or skin drag). We consider the following: reasons why objects in forward motion slow down; effects of aerodynamic drag on cyclists and formula 1 racing cars; evolution of underwater predators with streamlined shapes; how dolphins have evolved to reduce skin drag. ## Gravity, Mass and Weight How astronauts’ mass remains constant no matter what planet they visit; how weight would change on different planets as a result of differing forces of gravitational attraction. How measuring your weight actually measures the force of gravitational attraction between you and the planet you are visiting. A ‘true’ story about a quick way Homer Simpson could lose weight visiting different planets! ## Is there force of gravity in space? This science teaching resource considers the issue of ‘weightlessness’ and addresses the common misconception that ‘weightlessness’ means there can be little or no gravity in space.The reasons why astronauts appear to ‘float’ in space are explained; rockets need to reach high velocities in orbit and the spherical shape of the Earth means that the surface of the Earth is forever disappearing. ## Understanding Gravity and Mass An introduction to the force of gravity. The meaning of ‘mass’ and how we need to understand ‘mass’ before can understand ‘gravity’. Gravity is discussed with reference to planet earth, the moon and the Solar System. We look at examples of gravitational forces and how the forces of gravity affect our everyday lives. The gravitational force the sun exerts on the planets in our solar system. ## Electrical Charges and Static Electricity We look at examples of static electricity; the meaning of static electricity; revisiting magnetism; electromagnetic forces behind static electricity using the example of rubbing hair with a balloon; we observe how hair is attracted to the balloon. We explain the effects of friction and how negative electrical charges migrate to the balloon leaving the girl’s hair with excess of positive charges. ## Triboelectric Series Explained How amber is fossilized tree resin; how the ancient Greek philosopher Thalus of Miletes was the first recorded person to observe static electricity in action in 600BC; how he used amber in an ancient static electricity experiment; the meaning of the ‘triboelectric’ series; what the triboelectric series tells us; which materials have a tendency to become positively or negatively charged. ## Static Electricity Experiments In this science article we look at two different simulations which enhance students’ understanding of static electricity; one of the simulations explains how and why balloons stick to a wall and the other one explains how and why after walking across acarpet and touching a metal door handle you can get an electric shock; links to other websites with other static electricity experiments are suggested. Translate »