MOTION AND FORCE
QUESTIONS
MECHANICAL
TERM
EXPLANATION
EXAMPLE FROM
SPORT / PE
LINEAR MOTION
A
TOBOGGANIST
B
C
GYMNAST
PERFORMING A GIANT
CIRCLE ON THE HIGH
BAR
GENERAL MOTION
D
E
FORCE
A PUSH OR PULL THAT F
ALTERS, OR TENDS
TO ALTER, THE STATE
OF MOTION OF A
BODY
1.
2. LIST FIVE THINGS A FORCE CAN DO
AND GIVE AN EXAMPLE OF EACH.
3. DEFINE CENTRE OF MASS
4. GIVE AN EXAMPLE FROM PE/SPORT
WHEN AN ATHLETE’S CENTRE OF
MASS WOULD BE LOCATED:
a) INSIDE THEIR BODY
b) OUTSIDE THEIR BODY
5.WHY DOES THE LOCATION OF THE
CENTRE OF MASS CHANGE?
6. EXPLAIN BRIEFLY THE CONCEPT OF THE
LINE OF GRAVITY AND ITS LINK TO
STABILITY.
7. A TENNIS PLAYER MIGHT WANT TO IMPART
TOP SPIN TO THE BALL AT CONTACT.
EXPLAIN HOW THIS MIGHT BE ACHIEVED.
8. LIST THREE PRINCIPLES THAT ALLOW A
PERFORMER TO REMAIN STABLE.
9. NEWTON’S 1ST AND 2ND LAWS OF MOTION
ARE SOMETIMES REFERRED TO BY
DIFFERENT NAMES. IDENTIFY THE
ALTERNATIVE NAMES.
LAW
LAW
NUMBER
EXAMPLES
FROM SPORT
A BODY_______ IN A STATE
OF REST OR ________
________ UNLESS ACTED
UPON BY AN _________
_______.
1.
2.
FOR EVERY ________
THERE IS AN _______
AND _________ ________
1.
2.
WHEN A _____ ACTS ON AN
OBJECT THE RATE OF
CHANGE _______
EXPERIENCED BY THE
OBJECT IS ______ TO THE
_______ OF THE FORCE AND
TAKES PLACE IN THE
_______ IN WHICH THE
FORCE ACTS.
1.
2.
MOTION AND FORCE
ANSWERS
MECHANICAL
TERM
EXPLANATION
EXAMPLE FROM SPORT / PE
LINEAR MOTION
WHEN A BODY MOVES IN A
STRAIGHT OR CURVED LINE
WITH ALL ITS PARTS
MOVING THE SAME
DISTANCE IN THE SAME
DIRECTION AT THE SAME
SPEED.
TOBOGGANIST
ANGULAR MOTION
WHEN A BODY OR PART OF
A BODY MOVES IN A CIRCLE
ABOUT A PARTICULAR
POINT CALL THE AXIS OF
ROTATION.
GYMNAST PERFORMING A
GIANT CIRCLE ON THE HIGH
BAR
GENERAL MOTION
A COMBINATION OF LINEAR
AND ANGULAR MOTION
EG. RUNNING – ARMS /
LEGS = ANGULAR AS THEY
ROTATE ABOUT THE JOINT.
TORSO FOLLOWS A LINEAR
PATH ALONG THE STRAIGHT
FORCE
A PUSH OR PULL THAT
ALTERS, OR TENDS TO
ALTER, THE STATE OF
MOTION OF A BODY
EG. FORCE APPLIED TO
TRAMPOLINE ALLOWS
DOWNWARD PHASE TO
CHANGE TO THE NEXT
UPWARD PHASE.
1.
2. LIST FIVE THINGS A FORCE CAN DO AND GIVE AN EXAMPLE OF EACH.
A FORCE CAN CAUSE A:
A. BODY @ REST TO MOVE => FORCE
EXERTED TO RUGBY BALL TO GET IT
OVER THE POSTS
B. BODY TO CHANGE DIRECTION =>
GOALKEEPER APPLIES A FORCE TO
THE BALL THE STOP IT ENTERING
THE GOAL
C. BODY TO ACCELERATE => FOR A
SPRINT FINISH AN ATHLETE APPLIES
GREATER FORCE TO THE GROUND
D. MOVING BODY TO DECELERATE =>
TAKING A CATCH IN CRICKET
E. FORCE CAN CHANGE AN OBJECTS
SHAPE => A JUMP ON A SPRING
BOARD WILL CAUSE THE DIVING
BOARD TO BEND
3. DEFINE CENTRE OF MASS
THE CoM IS AN IMAGINARY POINT AT
WHICH THE BODY IS BALANCED IN
ALL DIRECTION.
4. GIVE AN EXAMPLE FROM PE/SPORT WHEN AN
ATHLETE’S CENTRE OF MASS WOULD BE
LOCATED:
a) INSIDE THEIR BODY
BALANCING IN A HANDSTAND
b)
OUTSIDE THEIR BODY
PIKE JUMP IN TRAMPOLINING
5. WHY DOES THE LOCATION OF THE
CENTRE OF MASS CHANGE?
THE POSITION OF THE CoM CHANGES
WITH CHANGES IN BODY POSITION
6. EXPLAIN BRIEFLY THE CONCEPT OF THE LINE OF GRAVITY AND ITS LINK TO STABILITY.
THE LoG IS AN IMAGINARY LINE THAT ORIGINATES
FROM THE CoM AND TRAVELS VERTICALLY
DOWNWARDS TOWARDS THE GROUND.
IF THE LoG FALLS TO THE:
i.
ii.
iii.
CENTRE OF THE BASE OF SUPPORT THE BODY
IS AT ITS MOST STABLE.
EDGE OF THE BASE OF SUPPORT THE BODY
BECOMES LESS STABLE
OUTSIDE OF THE BASE OF SUPPORT THE BODY
BECOMES UNSTABLE
7. A TENNIS PLAYER MIGHT WANT TO IMPART TOP SPIN TO THE BALL AT CONTACT. EXPLAIN
HOW THIS MIGHT BE ACHIEVED.
THE TENNIS PLAYER MUST EXERT A FORCE THAT TRAVELS
OUTSIDE THE TENNIS BALL’S CENTRE OF MASS. THIS IS
CALLED AN ECCENTRIC FORCE.
8. LIST THREE PRINCIPLES THAT ALLOW A PERFORMER TO REMAIN STABLE.
i. THE LOWER THE CoM THE MORE STABLE THE BODY
ii. THE BIGGER THE BASE OF SUPPORT THE MORE STABLE THE
BODY
iii. THE CLOSER THE LoG TO THE CENTRE OF SUPPORT THE
MORE STABLE THE BODY.
iv. THE MORE POINTS OF CONTACT THE MORE STABLE THE
BODY
v. THE GREATER THE MASS THE MORE STABLE THE BODY
9. NEWTON’S 1ST AND 2ND LAWS OF MOTION ARE SOMETIMES REFERRED TO BY
DIFFERENT NAMES. IDENTIFY THE ALTERNATIVE NAMES.
1ST LAW = LAW OF INERTIA
2ND LAW = LAW OF ACCELERATION
LAW
A BODY CONTINUES IN A
STATE OF REST OR
UNIFORM VELOCITY UNLESS
ACTED UPON BY AN
EXTERNAL FORCE.
FOR EVERY ACTION
THERE IS AN EQUAL
AND OPPOSITE
REACTION.
WHEN A FORCE ACTS ON AN
OBJECT THE RATE OF
CHANGE MOMENTUM
EXPERIENCED BY THE
OBJECT IS PROPORTIONAL
TO THE SIZE OF THE FORCE
AND TAKES PLACE IN THE
DIRECTION IN WHICH THE
FORCE ACTS.
LAW NUMBER
1
3
2
EXAMPLES FROM SPORT
1. GOLF BALL ON A TEE
UNTIL HIT
2. SPRINTTER IN BLOCKS
UNTIL FORCE IS APPLIED
TO THE BLOCKS
1.TAKE OFF IN HIGH JUMP
THE ATHLETE EXERTS A
DOWNWARD FORCE TO THE
GROUND THAT EXERTS AN
EQUAL AND OPPOSITE
UPWARD FORCE TO THE
JUMPER = LIFT
2. ROCK CLIMBER – AS
ABOVE
1. THE HARDER A BALL IS
KICKED THE FASTER /
FURTHER IT GOES, IN THE
DIRECTION IN WHICH IT WAS
HIT.
2. WHEN RETURNING A
SERVE THE BALL GOES
FASTER IF THE RECEIVER
HITS IT HARDER AND IT WILL
ALSO GO IN THE DIRECTION
IN WHICH IT WAS HIT.