spin and magnus effect

Question 1

define magnus force

Answer 1

a force created from a pressure gradient n opposing surfaces of a spinning body moving through the air

Question 2

define magnus effect

Answer 2

creation of an additional magnus force on a spinning projectile which deviates from the expected flight path

Question 3

why is the magnus effect used in sport

Answer 3

to mislead the opposition

Question 4

how is spin created on an object

Answer 4

apply an external eccentric force outside the centre of mass

Question 5

how is topspin created

Answer 5

eccentric force applied above the centre of mass

Question 6

how is backspin created

Answer 6

eccentric force applied below the centre of mass

Question 7

how is a sidespin hook created

Answer 7

eccentric force applied right of the centre of mass causing it to deviate to the left

Question 8

how is a sidespin slice created

Answer 8

eccentric force applied left of the centre of mass causing is to deviate to the right

Question 9

draw an airflow diagram of topspin

Answer 9

Question 10

explain how topspin is created and the effect it has on the flight of the ball

Answer 10

• external eccentric force is applied obove the centre of mass so…
• upper surface of projectile rotates towards the oncoming air flow which opposes motion, decreasing velocity of the air flow creating a high pressure
• the lower surface of the projectile is rotating in the same direction as the air flow, increasing the velocity if the air flow and creating a low pressure
• a pressure gradient forms creating a downward magnus force
• this causes the projectile to dip in flight giving it less time in the air as the flight path shortens creating a non-parabolic flight path

Question 11

evaluate the effect of topspin on the flightpath

Answer 11

1. effect: makes flightpath shorter
   advantage: can hit ball harder and till goes in e.g. topspin drive in table tennis
   disadvantage: can lose distance e.g. drive in golf
2. effect: makes ball dip in flight
   advantage: can hit ball higher oover obstacles and still go in e.g. volley over GK in football
   disadvantage: if not hit high enough the ball will hit the obstacle e.g. topspin dirve in tennis hitting the net

Question 12

draw a free body diagram for topspin

Answer 12

Question 13

draw a resultant force diagram for topspin

Answer 13

Question 14

draw an airflow diagram for backspin

Answer 14

Question 15

explain how backpin is created and the effect it has on the flight of the ball

Answer 15

• external eccentric force is applied below the centre of mass so…
• lower surface of projectile rotates towards the oncoming air flow which opposes motion, decreasing velocity of the air flow creating a high pressure
• the upper surface of the projectile is rotating in the same direction as the air flow, increasing the velocity if the air flow and creating a low pressure
• a pressure gradient forms creating a n upwards magnus force
• this causes the projectile to hang in the air which allows the flight path to lengthen creating a parabolic flight path

Question 16

evaluate the effect of backspin of the flight path

Answer 16

1. effect: makes flight path lengthen
   advanatge: ball can be hit further e.g. goal kick in football
   disadvantage: ball travels too dar before landing e.g. sliced backhand in tennis
2. effect: backspin makes ball hang in the air
   advantage: gives more time to recover before the next shot e.g. defence in table tennis
   disadvantage: give opponent more time to attack e.g. opponent can move into volley in tennis
3. effect: ball stops on landing
   advantage: makes opponent move further e.g. dropshot in tennis
   disadvantage: easier for opponent to attack

Question 17

draw an airflow diagram for the sidespin hook

Answer 17

Question 18

draw an airflow diagram for the sidespin slice

Answer 18

Question 19

evaluate the effect of sidespin of flight path

Answer 19

1. effect: makes ball swerve in flight
   advanatge: can move ball around obstacles e.g. free kick around wall in football
   disadvantage: ball can deviate too far e.g. football free kick misses the goal as swerve too far

Question 20

evaluate the effect of topspin of the bounce

Answer 20

1. effect: topspin makes the ball shoot forward when bouncing
   advanatges: keeps opponent bacl/ from attacking e.g. tennis AND can keep ball lower e.g. drive in tennis over the net

Question 21

evaluate the effect of backspin on the bounce

Answer 21

1. effect: backspin makes the ball sit up on bouncing
   advantages: drop shots with backspin make opponent move further e.g. tennis AND gives more control over the ball on landing e.g. pitch in golf
   distadvantage: easy for an opponent to attack e.g. tennis

Question 22

evaluate the effect of sidespin on the bounce

Answer 22

1. effect: does not cause deviation on bouncing
   advantage: ball carries on swerving after bouncing e.g. side slice serve in tnenis
   disadvantage: ball can swerve too much after bouncing e.g. low shot in football