During a collision between 2 wrestlers of different weights what will happen to the forces exerted on each of them?
Both wrestlers apply same amount of force on each other just in opposite directions
1 of 36
What forces act upon a football while it's in flight after being kicked?
Weight, lift and drag
2 of 36
What can you do to reduce parallax error when undertaking 2D video analysis?
Use a longer focal lens
3 of 36
What happens to gait during running?
There is a period in the stride where neither foot is in contact with the ground- flight phase and this increases step length
4 of 36
How can you describe newtons 1st law?
An object's resistance to change in it's state of motion
5 of 36
How do you work out velocity from mass and momentum?
Momentum/Mass= Velocity
6 of 36
What are the contact forces?
Impact, friction and fluid dynamics
7 of 36
What are the non contact forces?
Gravity, electromagnetism, strong and weak nuclear forces
8 of 36
What is the definition of pressure (pascals)?
It is the measure of the distribution of force over a surface area
9 of 36
How do you work our pressure?
Force/Area
10 of 36
What is the conservation of momentum in collisions?
The total momentum before collisions is the same as after collisions
11 of 36
How can the conservation of momentum be applied to sport?
In tackling- to oppose a player heading for you you have to match their momentum
12 of 36
What happens when a ball hits the floor?
It is deformed and then undergoes restitution
13 of 36
What does high restitution mean?
Less energy is lost on impact- more is returned
14 of 36
What type of ball would have high restitution?
A bouncy rubber ball
15 of 36
What is the ratio of rebound to impact velocity
-e= Vr/Vi
16 of 36
What is e?
The coefficient of restitution- tells us about energy loss during impacts
17 of 36
What does a COR of 0 mean?
All energy is lost during the impact
18 of 36
What factors effect the COR?
Properties of interacting objects (kinetic/potential/strain energy), velocity and temperature
19 of 36
What is a 'sweet spot'?
An impact point of a bat or racquet which minimises the forces transmitted to the hand
20 of 36
What is the centre of percussion?
The point of contact where linear and angular motions at the handle are cancelled out
21 of 36
What does the sweet spot depend on the locations of?
Centre of percussion, centre of power and the primary nodal point
22 of 36
What is the primary nodal point?
Point on a racquet where when hit it will not excite vibrations
23 of 36
What is the equation for lift?
1/2pU^2SCl
24 of 36
What do the letters in the lift equation stand for?
p= air density U= speed of air S=area Cl= lift coefficient
25 of 36
What is the equation for drag?
The same as lift but using the drag coefficient instead of lift
26 of 36
What happens when something is above the critical angle of attack?
It will stall meaning; Flow separates, drop in lift and increase in drag
27 of 36
What is the magnus effect?
The generation of a sideways force when a spinning object travels through the air
28 of 36
What is the equal transit theory (Bernoulli)?
Flow has to travel further over a curved upper surface of an object so the speed of air increases to meet at trailing end- faster air exerts less pressure than slow air meaning the slow air underneath creates lift
29 of 36
What does the equal transit theory not explain?
Upside down flight, flat wings and forces on a rotating object
30 of 36
What does Bernoulli say about lift?
Pressure is inversely proportional to the speed of flow
31 of 36
What determines drag coefficient?
Shape of object, angle of attack and reynolds number
32 of 36
What are the 3 types of drag?
Profile, Induced (due to lift) and Skin (friction)
33 of 36
What is the boundary layer?
A thin layer of fluid in contact with surface which is subject to shear force
34 of 36
What is the equation for Reynolds number?
Re= puL/u
35 of 36
What does the Reynolds number describe?
Flow characteristics at different speeds
36 of 36
Other cards in this set
Card 2
Front
What forces act upon a football while it's in flight after being kicked?
Back
Weight, lift and drag
Card 3
Front
What can you do to reduce parallax error when undertaking 2D video analysis?
Comments
No comments have yet been made