# Newtonian Mechanics & Pressure Flashcards

What is a Newton?

A force that increases the velocity of one kg by one meter per second every second.

N = kg.m/s(sq)

Define acceleration

The rate of change of velocity

Define inertia

The tendency of an object stationary or in motion to resist an change in velocity.

What is momentum?

Quantity of motion; a product of an objects mass and its velocity

P = mv

Newton’s first law

In the absence of external forces, an object at rest remains at rest and an object in motion continues in motion with a constant velocity.

Newton’s second law

The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

Newton’s third law

If two objects interact, the force applied by an object A and on object B will be equal but opposite to the direction of the force exerted by object B on object A. Ie for every action there is an equal and opposite reaction.

Pressure equation

Force/ area

Define a pascal

Pressure of one Newton acting over an area of one metre square.

Conversion of 1 kPa to millimetres of mercury?

1 kPa = 7.5mmHg

What is the difference between absolute pressure and gauge pressure?!

Gauge pressure is the reading on the cylinder gauge.

Absolute pressure is the total pressure in the cylinder. This includes atmospheric pressure.

Formula for absolute pressure?

Absolute pressure = gauge pressure + atmospheric pressure

What is the absolute pressure of a full oxygen cylinder?

137 bar + 1 bar

= 138 bar (or 13800 kPa)

What is intrapleural pressure during normal inspiration?

Is a few cmH2O (approx 10cmH2O = 1kPa) below atmospheric pressure.

101 kPa - 1 kPa = 100 kPa

How does a Bourdon gauge work?

A gas at a high pressure enters a coiled tube (bourdon tube) causing it to uncoil.

As the tube uncoils, the motion is transferred through a linkage to a gear train connected to a pointer which moves over a scale on a dial.