Forces assessment revision

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• Forces
• Scalars and vectors:
• Scalar quantities have size or magnitude but direction is not specified. For example: -distance -speed and mass.
• Vector quantities have magnitude and a specific direction. For example: displacement, velocity, force.
• contact and non contact forces
• Contact forces are forces that act between two objects that are physically touching each other. such as friction,      resistance and tension.
• Non contact forces are forces that act between two objects that are not physically touching each other. such as magnetism and gravity
• Static flyer practical equiptment list:  Cotton towel, plastic bag, scissors, balloon.
• Static flyer steps: 1-cut off a section from the open end of the bag. 2-blow up a balloon and tie the end. 3- Rub the towel on the balloon 4-Rub the towel on the plastic. 5-Suspend the plastic cover over the balloon and let go
• Newtons third law: 'when two objects interact with each other they exert equal and opposite forces in each other.
• Work Done
• when a force makes an object move by a distance you can say that work is done on the object. The work is EQUAL to the energy transferred to the object.
• Work done equation:
• Work done= force x distance
• parallelogram and resolution forces
• resultant forces= a single force that has the effect of all forces acting on an object.
• center of mass and gravity
• Weight (N) The weight of an object and the mass of an object are directly            proportional.
• weight of an object = weight(n)=     mass(kg) x gravitational field strength (n/kg)
• extension of a spring
• there is  linear relationship between force and extension. The extension of a sprint is directly proportional to the force.
• By overstretching the spring we have exceeded the limit of proportionality
• Hookes law: force=spring constant x extention        Foxes Kill Elephants
• work done: 0.5 x spring constant(n/m) x extension squared (m)
• extention = new length - origional length