Topic 9 Forces and their effects

• a force is something that affects the motion or shape of an object
• some forces can act at a distance, without any contact between bodies, due to the action of a field
• forces can also act when objects touch, friction for example occurs when objects rub against each other
• contact forces push touching objects apart, and are responsible for supporting objects when they're lying stationary on the ground
• Vector Quantities are quantities with both direction and magnitude, eg velocity or displacement
• scalar quantities are quantities with only magnitude, eg mass
• Newtons Third Law states that when one object exerts a force on another object, the second object exerts an equal and opposite force
• The space around an object where it can affect other objects is a force field
• if the forces acting in opposite directions are equal in size, then there will be no resultant force: the forces are BALANCED
• We can make an object rotate by applying one force or a system of forces to an object.
• when you push a door, the door will turn on its hinges. The turning effect of the force causes the object to rotate.
• Moment of a force (Nm) = Force (N) * Distance normal to the direction of the force (m)
• Principle of Moments = The sum of clockwise moments = The sum of anticlockwise moments
• For a system to be at rotational equilibrium,the sum of all torques acting on a system must equal zero.
• Torque is a measure of the force that can cause an object to rotate about an axis.
• A turning force is called a moment
• If Gear A has 8x the amount of teeth as Gear B, a complete turn of A turns B 8 times
• A lever is used to transfer a force by pivoting around a point
• As one gear rotates, its teeth interlock with the other gear making it rotate X times as much
• Heat is a wasted energy source in some cases due to friction. This friction can be decreased by lubrication by using oil or grease.