Forces

• Scalar quantities have magnitude only.
• Vector quantities have magnitude and direction.
• Forces are shown with an arrow indicating direction and the length indicating magnitude.
• Contact forces are forces that act when one body touches another.
• Non-contact forces are forces that act when bodies are physically separated.
• Weight is a force that acts on an object due to gravity.
• The strength of the gravitational field determines the weight of an object.
• The calculation for weight is: mass(kg) * gravitational field strength(N/kg).
• Acceleration is the speeding up of something.
• A resultant force is a single force which replaces several other forces with the same affect.
• To create a resultant force, add forces going in the same direction and subtract forces that go in different directions.
• Freebody diagrams show all forces acting on a body.
• A resolving force is a force that can be broken down into two component forces acting at right angles to each other.
• The equation for workdone is force * distance.
• Applying 1 force sets an object in motion.
• An object is in equilibrium if the resultant force and resultant moment are both equal to zero.
• 1 Joule equals 1 newton-metre.
• If a spring is stretched beyond its limit of proportionality, the forces do not return to their original length and shape.
• When a spring is released, the energy is transferred to other stores.
• Energy transfer occurs when energy moves from one energy store to another energy store.
• Two forces are needed to bend, stretch or change the shape of an object.
• The elastic potential energy stored in a spring is equal to the work done in stretching the spring.
• The equation for elastic potential energy (J) is 0.5 * spring constant (n/m) * extension2 (m).
• Force = extension x spring constant.
• The force applied on a spring is directly proportional to the extension of the spring.
• Hook’s Law states that the extension of an elastic object, such as a spring, is directly proportional to the force applied, provided that the limit of proportionality is not exceeded.
• Workdone is the amount of energy transferred when an object moves due to a force, causing energy to move from one store to another.
• The amount of force needed to move an object a certain distance is known as the force required.
• More teeth on a gear mean forces are spread over a larger area, resulting in smaller forces.
• When forces act along different lines, they rotate an object.
• Gears are used to increase or decrease the rotational effects of force.
• A liquid with great weight means it has high density.
• A small distance and a heavy force are not equal.
• Forces have to be equal for an object to be balanced.
• Upthrust is an upward force that a fluid exerts on a body floating in it.
• The equation for pressure is p = force/area.
• p(pa) = height of column (m) * density of liquid (kg/m3) * gravitaional field strength (N/kg).
• Moments are the turning effects of forces.
• A partially or totally submerged object experiences a greater force on the bottom surface than on the top surface, this is known as floating.
• Pressure is the force normal to a surface/area of that surface.