jumping and rowing

Question 1

Analysis of a Vertical Jump

Answer 1

The Quiet Phase
 The Unweighting Phase
 The Braking Phase
 The Propulsive Phase
 The Flight Phase
 The Landing Phase

Question 2

Newton’s 3rd Law: Action-Reaction

Answer 2

to every action there is an equal yet opposite reaction”
If object A exerts a force on another object B, then object B exerts the
same force on object A but in the opposite direction
Walking: person exerts an action force on the ground, whilst
the ground exerts a ‘reaction force’ on the person
Floyd chapter 3 provides good description of ground reaction forces

Question 3

quiet phase

Answer 3

Period before the movement begins – athlete’s weight can be determined

Question 4

unweighting phase

Answer 4

First movement, when the athlete drops down and “unweights.”
o Force lower than body weight - essentially in a free-fall
o Negative velocity that continues to increase in the negative direction
(downward acceleration)

Question 5

braking phase

Answer 5

Athlete starts to apply force to slow and then stop the “free fall”
of the unweighting phase.
o Athlete’s centre-of-mass velocity is still negative but ascends
toward 0 m/s (upward acceleration)

Question 6

propulsive phase

Answer 6

Occurs after the athlete has fully stopped moving downward.
o When the athlete actively propels themselves upwards to jump.
o Propulsive phase is defined by positive velocity until take-off

Question 7

flight phase

Answer 7

Begins when the athlete takes off from the ground
o No ground reaction force

Question 8

the landing phase

Answer 8

Begins when the athlete descends from the air and lands back on the plate

Question 9

Hip Extensor muscles

Answer 9

Gluteus Maximus
Mono-articular
O: Illium, sacrum, coccyx
I: Lateral greater trochanter

Hamstrings (bi-articular)
All originate on ischial tuberosity (short
head on the femur); insert on tibia (SM &
ST) or Fibula (Biceps Femoris)