Ms Moore Topic test Flashcards
Define Linear motion
Motion in a straight line
All parts move the same distance at the same time in the same direction
Give an example of linear motion
Tennis serve, downhill skier, shot put during flight
Define angular motion
Angular motion is the rotation of an object about a fixed axis
How is linear motion created?
Direct force applied through the balls centre of mass
Describe angular motion
Movement around a fixed point or axis (of rotation)
Generated by an eccentric force or force that travels outside the centre of mass or gravity
Using a sporting example, explain how a performer can move their centre of mass outside the body to effectively perform a named skill (3)
A front summersault at take off weight is thrown
Centre of mass will follow predetermined flight path
Effect of technique on centre of mass e.g. CoM is out in front of body during take-off
Describe a factor that affects the the position of the centre of mass
The distribution of the body mass affects the position of the centre mass
(Changing body position) e.g: A diver raises their arms above their head which raises their centre of mass or a sprinter moves their weight forward in set position to get their centre of mass closer to the start the line
(Distribution of mass/differing mass) e.g: A cyclist may have a lower centre of mass due to a high level of muscularity in their legs compared to upper body
Define moment of inertia and explain the factors that affect the moment of inertia of a rotating body in sport. (3)
Resistance of a rotating body to change it state of angular motion the rotational equivalent to inertia
sum of mr^2
Depends on the mass of an object
Greater the mass of object the greater is its moment of
Depends on the distribution of mass from the axis of rotation
The further the mass is away from the axis of rotation the greater the moment of inertia
The greater the moment of inertia the greater the force required to increase or decrease rate of rotation
In order to achieve success in swimming, performers must have good technique and excellent fitness. They must also minimise the effect of drag in the water. Identify and evaluate ways that a swimmer can minimise drag. (6)
Reduce frontal cross-sectional area
An effective technique as swimmer keeps body as flat as possible or freestyle stroke minimises frontal cross section area
Streamline or shape
Smooth flow of water around a tear-drop shape
Freestyle very streamlined vs breast stroke less so
Reduce surface effects
Easily done by wearing smooth swimsuits
Reduce speed / velocity
Not a feasible method as speed key to success
Explain how backspin causes a deviation in flight path and the bounce of a table tennis ball. (5)
Air travels further over the top of the ball
Therefore, air travels faster over the top of the ball
Airflow accelerated by direction of spin
venturi created above the ball
This creates low air pressure over the top of the ball
Called the magnus force
Counteracts the force of weight and the ball stays in the air for longer
Cover great distance
surface of the ball trying to slide forwards on ground
Friction acts in opposite direction
Resultant force acts backwards
Causes ball to decelerate
Ball ‘sits up’
Explain how this net force causes a deviation in the normal flight path of a fasting moving shuttle (2)
Shuttle decelerates
Resultant net force is same direction as air resistance and the opposite direction of motion
Resultant net force shows direction and size of acceleration of shuttle
Critically evaluate the backspin in sport (5)
Flight path lengthens
Therefore ball can be hit further e.g. goalkick in football
- Ball travels too far before landing
- Ball travels slower in the air to reach same point
- This gives more time for opponent to intercept
- Easier for an opponent to attack
+ Gives more time to recover before next shot
+ Easier for teammate to control
+ Drop shots with backspin make
Explain the relationship between the size of the vertical forces and their impact on the size of the resulting vertical jump (2)
R > W means there is an unbalanced force acting on basketball
R > W means there is a upward force
Therefore there is an upwards acceleration
The bigger the reaction force, the greater the net upward force
Identify three factors that affect the horizontal distance travelled by a projectile. (3)
Height of release
Speed of release
Angle of release
Air resistance
Explain how spin causes the flight path of the ball to deviate (2)
Effect of swerve is magnus force
Caused by a pressure of gradient from high to low
Air travels further and faster on low-pressure side of ball
State bernoullis principle
The higher the velocity of air flow the lower the (surrounding) pressure or all gases move from an area of high to low pressure / down a pressure gradient
Apply bernoullis principle to the design of Formula One racing cars. (5)
Reverse aerofoil is used
Angle of spoiler creates a downward force
Air travels at a higher speed under spoiler
Causing pressure to be lower under spoiler
Air travels at lower speed over spoiler
Causing pressure to be higher above spoiler
Front wing diverts air further underneath chassis of the car
Enabling car to hold the road
Identifytwotypes of spin and the effect of each on a table tennis ball in flight. (2)
Top spincauses ball to shorten flight path
Back spincauses ball to lengthen flight path
Side spincauses ball to swerve
Atrampolinist performs a front somersault by creating angular motion. Define angular motion and explain how it is generated to produce a somersault. (2)
Movement of a body in a circular path about an axis of rotation
Eccentric force applied
Explain, using the angular analogue of Newton’s first law of motion, the concept of conservation of angular momentum. (3)
A body will continue to rotate with constant angular momentum….
…unless acted on by an eccentric force
Angular momentum = moment of inertia × angular velocity
Once in flight- any change in MI will cause a change in AV to conserve angular momentum
e.g. if a diver tucks, MI is reduced so AV increases
which means angular momentum is a conserved through flight shape
Performer can manipulate body shape to change MI and AV as AM remains constant
A gymnast performs a handstand as part of their routine. Identify the vertical forces acting on the gymnast and explain their relationship during the handstand (3)
Weightandreactionforce
Weight = Reaction
Forces are equal in sizeandopposite in direction
Define angular motion and explain how it is generated to produce a somersault. (2)
Movement of a body in a circular path about an axis of rotation
Eccentric force applied
Describe the factors that affect the size of moment of inertia of the trampolinist during the front somersault (2)
mass
distribution of mass fromaxis of rotation
Explainthreefactors that affect the horizontal distance travelled by the shot in flight. (3)
Speed of release – the greater speed of release the greater the distance
Angle of release - 45° optimal angle
Height of release – the greater therelease heightthe greater the distance travelled
