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| Question | Answer |
| Newtons First Law | When the unbalanced (or resultant) force on an object is zero, 'a' will also be zero. An object with zero acceleration will either be stationary or moving on a straight line at a steady speed. |
| Newtons Second Law | When an unbalanced force acts on an object is causes an "a". The acceleration is directly proportional to the size of the force, 'F', and inversely proportional to the mass of the object. F=ma |
| Momentum | -All objects have momentum when they are moving. The greater the momentum, the most impact the object will have of it hits something. |
| Energy | -Kinetic Energy: The energy an object has because it is moving. -Gravitational Potential Energy: is gained by an object when it os lifted vertically against the force of gravity. -Elastic Potential Energy: is stored when a spring is stretched or compressed by a certain distance. |
| Conservation of Energy | The energy cannot be created or destroyed but can be changed from one form to another. |
| Work | Transforming energy from one form to another is called doing work. W=Fd |
| Impulse | A change in 'v' means there is a change in momentum (p=mv). The change in momentum is called impulse of the force. |
| Conservation of Momentum | In collision or explosions, the total momentum of the objects involved is conserved (ie. the same as before and after). This happens provided there are no unbalanced external forces such as friction or gravity affecting the objects. |
| Conservation of Energy | Although Momentum might not be conserved during a collision, it is common the find that energy is not. Energy may be lost to heat due to friction or even sound. |
| Inelastic/Elastic collisions | Inelastic Collision: Collisions in which there is a loss of energy Elastic Collision: Collisions in which the total energy of the objects remain unchanged |
| Centre of Mass | Def: This is a point of an object where the total mass acts if its concentrated. (Also called centre of gravity) |
| Centre of Mass (Cont.) | The object will always hang so that the centre of gravity is directly below the point of suspension, since only at this position will the Fg of the object and Tension force of the string will be in equilibrium. |
| Calculating the position of C.O.M | Equation: |
| Centre of Mass (Cont. part 2) | EQUATION: |
| Centre of Mass (Cont. part 3) | If a system is isolated (no external forces), then its 'p' will not change. Most cases the "m('s)" of the individual particles in the system do not change, therefore velocity of the C.O.M must remain constant. (C.O.M is closest to the heavier mass) |
| C.O.M and collisions | As objects collide, they both change their speed and direction, but the C.O.M moves with a constant velocity (ie. the same speed in the same direction). The 'v' of the C.O.M is unchanged by the collision. |
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