Fluid mechanics and projectile motion Flashcards
What is fluid mechanics/
the study of the forces acting on a body travelling through the air or water.
When does air resistance act on a body?
a body travelling at high velocity through air
WHat is the force of drag?
a force that opposes the direction of motion of a body through water.
What are the four main factors affecting the magnitude of air resistance and drag on a body?
- velocity
- frontal cross- sectional area
- streamlining and shape
- surface characteristics
How does velocity effect air resistance and drag?
- greater the velocity, greater the air resistance or drag
How does frontal cross sectional area effect drag + air reistance ?
larger the frontal cross sectional area, larger air resistance or drag
How does streamlining and shape effect air resistance and drag?
more streamlined and aerodynamic the shape of the body in motion, the lower the air resistance or drag
How does surface characteristics effect air resistance or drag?
smoother the surface, lower the air resistance or drag
What is projectile motion?
movement of a body through the air following a curved flight path under hte force of gravity
What is a projectile?
a body that is launched into the air losing contact with the ground surface
What four factors is the horizontal distance travlled by a projectile effected by?
- speed of release
- angle of release
- height of release
- aerodynamic factors
Explain how a the distance travlled by a projectile is mainly effected by speed of release?
This is due to newtons second law of acceleration. The greater the force applied to the projectile, the greater the change in momentum and acceleration of the projectile in air
Explain how angle of release effects the distance travelled by a projectile?
- if released at 90 will go straight up
- at 45 it is the optimal angle
- greater then 45, the projectile will peak to early
- less then 45, insufficient height
WHat is a parabola?
- uniform curve symmetrical about its highest point
In flight what is a projectile effected by?
weight and air resistance
What is a parabolic flight path?
a flight path symetrical about its highest point caused by the dominant weight force of a projectile
When would a parabolic flight path occur?
if weight is the dominant force and air resistance is very small
What is a non parabolic flight path?
a flight path asymmetrical about its highest point caused by the dominant force of air resistance on the projectile
WHen does a non parabolic flight path occur>
if air resistance is the dominant force and weight is very smal
How can the forces acting on a projectile in flight be represented?
a free body diagram
What are the three phases of motion within a flight path ?
- start of flight
- mid flight
- end of fligth
When will air resistence be greatest in flight?
at the start as the velocity is highest
WHat is a parallelogram of forces?
a parallelogram illustrating the theory that a diagonal drawn from the point where forces are represented in size and direction shows the resultant force acting
What is the resultant force?
- the sum of all forces acting on a body or the net force acting on the projectile
What happens if the resultant force is closer to the weight arrow>
the force of weight is dominant and therefore the flight path will be more parabolic
What does it show if the resultant forve is closer to the air resistance arrow?
the force of air resistance is dominant and therefore the flight path will be non-parabolic
What is the bernoulli principle?
creation of an additional lift force on a projectile in flight resulting from bernoulli’s conclusion that the higher the velocity of air flow, the lower the surrounding pressure
WHat is the effect of additional lift?
to increase the time the projectile hangs in the air, extening the flight path and horizontal distance covered
WHat is lift force?
an additional force created by a pressure gradient forming on opposing surfaces of an aerofoil moving through a fluid
As velocity of an aerofoil increases, where does pressure decrease?
- above the curved upper surface, low pressure created
- below the flat underneath surface, high pressure created
What is the angle of attack?
the most favourable angle of release for a projectile to optimise lift force due to the Bernoulli principle
What is the magnus effect?
creation of an additional Magnus force on a spinning projectile which deviated from the flight path
What is a magnus force?
a force created from a pressure gradient on opposing surfaces of a spinning body moving through air
What is a magnus force?
a force created from a pressure gradient on opposing surfaces of a spinning body moving through air
how is spin created?
- applying an external force outside the centre of the mass
What are the four types of spin?
- topspin, backspin, sidespin hook, sidespin slice
How is topspin created?
eccentric force applied above centre of mass
How is backspin created
eccentric force applied below center of mass
How is backspin created
eccentric force applied below center of mass
How is backspin created
eccentric force applied below center of mass
How is a sidespin hook created?
- eccentric force applied right of the centre of mass
How is a sidespin slice created?
- eccentric force applied left of the centre of mass
what effect does topspin have on magus force and flight path
- downward magnus force, shortening flight path
What effect does backspin rotation create on magnus force and flight path?
- upward magnus force, lengthening flight path
What effect does a sidespin rotation have on magnus force and flight path?
- slice creates right magnus force, flight path right
- hook creates left magnus force, flight path left
For a ball with topspin how is the extra magnus force created?
- upper surface of the projectile rotating towards the oncoming air flow (high pressure zone created)
- lower surface of the projectile rotating in the same direction as the air flow (low pressure zone created)
- pressure gradient forming and magnus force being created downwards
