PRESSURE

​

The standard definition of pressure in the world of physics is explained to be force per unit area. When an object is sitting on a surface, the force that is exerted on the surface is known as the “weight” of the object. You can also measure and observe the pressure of gases and liquids; the pressure of a gas is essentially the measure of the rate of molecular collisions with the walls of the container keeping the gas. The pressure of a fluid is a measurement of energy per unit volume; this becomes important when we begin to discuss blood pressure as it relates to the circulatory system. Your blood needs to move around the body to make sure it gets the oxygen and energy it needs, and this is done by your heart pumping in beats. When your blood moves through your body, it exerts a certain pressure by pushing against the walls of the blood vessels; the measure of this pressure is naturally referred to as your “blood pressure.”

​

WORK 

In order for there to be “work” done on an object, a force must act on the object that leads it to displace a certain distance. The equation for work can be expressed as W= (Force)x(Distance)x(cos theta). Theta in this equation represents the angle which is defined between the force and the displacement vector. The standard metric unit we use to quantify work is the Joule (J). One Joule is equal to one Newton of force which subsequently causes a displacement of one meter; this means that 1J= (1 Newton)x(1 meter). The work that is done is not related to the amount of time that the force needed to act on the object to cause said displacement. 

​

POWER

Power is defined as the rate in which work is done on an object. This means that power is measured as a ratio of work/time. Because of this definition, the equation used to calculate power is P= (Work)/(time), and the standard metric unit for power is defined as a “Watt”. Because a unit of power is defined by a unit of work divided by a unit of time, we can conclude that a Watt is essentially equivalent to a Joule/second. After manipulating this simple equation by substituting in the individual equations for work and power, we can conclude at the end that power can be equal set equal to the (Force)x(Velocity). 

​

CIRCUITS 

The circulatory system can be easily compared with the function of a traditional electric circuit. The arteries, veins, blood vessels and capillaries in our circulatory system are essentially working the same way as the wires work in an electric circuit. The same way the wires in a circuit are able to carry the electric current to all parts of the system, the blood vessels in our circulatory system are carrying the blood flow through our body. A battery or generator in an electric circuit is responsible for producing the voltage for the system that allows for the flow of current through the rest of the circuit. In the circulatory system, the heart is responsible for pumping the blood into circulation; the heart provides the pressure or force required to get the blood moving throughout the body. The blood that is now circulating throughout the body is supplying many organs and other systems with the resources they each need to continue to function. The blood that flows through your body must travel through vessels; the walls of these blood vessels can impact the flow, and the smaller the diameter of the vessel, the more resistance the blood flow experiences. As the heart pumps, much of the pressure that it exerts is used to help push the blood along through these often narrow vessels. Electrons in an electric circuit can also experience obstacles in its flow; as electrons attempt to move through the wires of the electric circuit system, atoms are often in the way and bump into these flowing electrons. Therefore, the wire itself offers resistance to the flow of the current of electrons through the electric circuit. Resistance is measured using the standard unit of an ohm (Ω). Electrical circuits can be constructed in series or in parallel. Smaller blood vessels in the circulatory system of the human body are similar to parallel circuits. These small blood vessels branch off from an artery and subsequently connect to a vein, where the blood is then returned to the heart. 

​

SERIES 

A circuit that is in series is a circuit in which the resistors are placed in a chain, so that the current that is flowing only has one path it can take. Because of the placement of the resistors, the current is measured to be the same through each of the resistors. When you want calculate the total resistance of the circuit in series, it is quite simply achieved by adding up the individual values of each resistor. Therefore the equation used to find the total resistance of a series circuit would be: Total Resistance = Resistance1 + Resistance2 + Resistance3 + ...

​

PARALLEL 

When a circuit is set up to be in parallel, the resistors are placed with their “heads” connected together, and their “tails” connected together. Unlike the current in a series circuit, the current in a parallel circuit is not fluid and breaks up. Some of the current flows along each of the parallel branches of the circuit, and then they come together when the branches meet up again at a certain point in the circuit. The amount that goes through each resistor is dependent upon the individual resistances. Because of this set up, we can measure the voltage across each of the resistors in parallel to be the same. To calculate the total resistance of the parallel circuit, you would have to add up the reciprocals of each resistance value, and then take the reciprocal of the total calculated amount. Therefore the equation used to find the total resistance of a parallel circuit would be: 1 / Total R = 1 / R1 + 1 / R2 + 1 / R3 +...