# Science - Force

 What is a force? This is something that can change the motion of an object State the SI unit for force The SI unit for force is the newton (N) How is force measured? Force is measured using a spring balance Explain what forces can do They can change the speed of an object They can change the shape and size of an object They can change the direction an object is moving in What is meant by contact forces? These are two objects that have to be in contact for these forces to occur eg. push, pull, friction and tension What is meant by non-contact forces? These are two objects that do not have to be in contact for these forces to occur eg. gravity Explain centre of gravity This is the point where the object balances What does an object need to have in order for it to be in stable equilibrium? A wide base A low centre of gravity What is meant by equilibrium? This is when all the forces are balanced in a body What is meant by stable? This is when an objects centre of gravity is inside the base of the object What is meant by unstable? This is when an objects centre of gravity is outside the base of the object What is meant by neutral? This is when an objects centre of gravity does not change What is a fulcrum? This is the turning point of an object What is a lever? This is any rigid body that rotates (free to move) about a fixed point called a fulcrum eg. see-saw Explain the law of the lever? This states that the sum of the clockwise moments equals the sum of the anticlockwise moments What is meant by a moment of a force? This is the rotation about the fulcrum Explain friction This is a force the opposes motion when two objects are place in contact State an advantage of friction It allows us to have grip when you walk, run and climb or when you alloy the brakes on a bike or in a car State a disadvantage of friction Wears away the soles of our shoes Wears away the tyres on our car and bicycles Explain how to reduce friction Lubrication is used to reduce the friction between two solids eg. oil and wax Surfers wax their surfboards to reduce the friction between the board and the water What are elastic objects? This is any object that is able to restore its shape after it has been stretched or compressed eg. springs and elastic bands What is meant by elastic limit? This is when elastic objects are extended to a point where they will not restore their shape Explain Hooke's Law This states that the extension of a spring is directly proportional to the applied force This is because the points give a straight line through the origin Authormshowley ID340438 Card SetScience - Force DescriptionForce Updated2018-05-26T22:26:08Z Show Answers