Week 11 - Defining Power

Question 1

Define mechanical power and the equation

Answer 1

Rate of work production/amount of work done over a period of time

Power (P) = Work (W) / time (t)

Power (P) = Force (F) x displacement (d) / time

Power (P) = Force (F) x velocity (v)

SI units for power are Watts (W) or Joules per second (J/s)

1W = 1J/s

Question 2

Why is power important?

Answer 2

In sport, excelling requires not only the ability to perform a large amount of work, but also the ability to do that work quickly e.g. weightlifters

Question 3

Two types of power

Answer 3

Positive (concentric) producing power, negative (eccentric) absorbing power

Question 4

How much power is produced by cleaning 30 kg at 3 m/s?

Answer 4

P = Fv

P = (30 x 9.81) x 3

= 882.9 Watts

Question 5

Is this the optimal weight when the same lifter can clean 80 kg at 2.5 m/s?

Answer 5

P = Fv

P = (80 x 9.81) x 2.5

P = 1962 W

To optimise power it is more advantageous to maximise force/train at a higher load

Question 6

To optimise power it is more advantageous to maximise force/train at a higher load

Question 7

Joints during running, which joint produces the most power in the stance phase?

Answer 7

Ankle

Question 8

Joints during running, which joint absorbs a lot of power during the weight bearing phase?

Answer 8

Knee

Question 9

Joints during running, which joint products most positive work during the swing phase?

Answer 9

Hip