Discussion in 'Olympics 2012' started by sues, May 1, 2013.
my son has been asked to do this for his homework..we cannot find out the answer
Total for the race, or per second?
Per second, Usain, over the whole race, Mo.
It's refreshing to have a homework question that is actually identified as such by the OP. Makes a change.
Depends on the length of the race though.
for the race.....we've just had a big discussion about it lol
This looks like the page you want
Apologies for the long c&p, but it's the key really:
A linear relationship exists at walking speeds of 3 to 5 km/hr of oxygen consumption but at faster speeds oxygen consumption rises making walking less economical.
Body mass can be used to predict energy expenditure with reasonable accuracy at walking speeds of 2 to 4 mph (3.2 to 6.4 km/hr). The following table details the amount of calories you will burn per minute for ranges of body mass (weight) and speed when you walk on a firm level surface (McArdle 2000)
Speed Body Mass
Kg 36 45 54 64 73 82 91
mph km/hr Lb 80 100 120 140 160 180 200
2.0 3.22 1.9 2.2 2.6 2.9 3.2 3.5 3.8
2.5 4.02 2.3 2.7 3.1 3.5 3.8 4.2 4.5
3.0 4.83 2.7 3.1 3.6 4.0 4.4 4.8 5.3
3.5 5.63 3.1 3.6 4.2 4.6 5.0 5.4 6.1
4.0 6.44 3.5 4.1 4.7 5.2 5.8 6.4 7.0
If your body mass is 64 kg and you walk at a speed of 5.63 km/hr then you will burn approximately 4.6 Calories/minute - if you walk for one hour you will burn 60 × 4.6 = 276 Calories
When running at identical speeds, a trained distance runner runs at a lower percentage of their aerobic capacity than an untrained athlete does, even though the oxygen uptake during the run will be similar for both athletes. The demarcation between running and jogging depends on the individual's level of fitness. Independent of fitness it becomes far more economical from an energy viewpoint to change from walking to running when your speed exceeds 8km/hr (5 mph). Above 8km/hr the oxygen intake for a walker exceeds the oxygen intake of a runner. At 10km the walker's oxygen (O2) uptake is 40 ml/kg/min compared to 35 ml/kg/min for the runner.
Diagram Reference: (McArdle 2000a) 
Body mass can be used to predict energy expenditure with reasonable accuracy when running on a firm level surface (road, track or grass). The amount of calories required to run 1 km equals your weight in kg (a runner of 78 kg will burn 78 Calories/km).
One litre of oxygen equals five calories so our 78kg runner utilises 15.6 litres of oxygen per kilometre.
The following table details the amount of calories you will burn per minute for ranges of body mass (weight) and speed when you run on a firm level surface (McArdle 2000b).
Speed Body Mass (Kg)
km/hr 55 65 75 85 95
8 7.1 8.3 9.4 10.7 11.8
9 8.1 9.8 11.0 12.6 14.4
10 9.1 10.8 12.2 13.6 15.3
11 10.2 11.8 13.1 14.7 16.6
12 11.2 12.8 14.1 15.6 17.6
13 12.1 13.8 15.0 17.0 18.9
14 13.3 15.0 16.1 17.9 19.9
15 14.3 15.9 17.0 18.8 20.8
16 15.4 17.0 18.1 19.9 21.9
Sure, I assumed it was for short vs. long races.
im assuming its for their own races, but j doesn't seem to know? not listening again probably!
Doesn't mention anaerobic activity e.g. 100M sprinting though.
thanks for that a massive help
Calories? You mean kilocalories surely?
I calorie = 1000 calories
I like joules.
Yes, but kilocalories are also known as "food calories".
No, that is true. That's bound to kick up again.
Can't we use Newton-metres?
mo for the simple reason the race is longer
no if you wanted to say amount of energy per lap we might be getting somewhere
Are you talking about who generates more kinetic energy, or whose body has more energy demands directly attributable to the race, including the 24 hours or so after the race? There are lots of other interpretations of the question too.
It's a question that has to be formulated really well to be meaningful - when I was in school we would get these questions and a lot of the marks came down to correctly identifying which question you were answering ie. you outline the question you are going to answer in detail and then answer it.
I would probably have taken the lazy route; outlined a simple form of the question, done some kinetic energy calculations and then discussed other possible interpretations of the question at the end - that sort of approach seemed to fit in well with the marking scheme.
Might not work for A-level sports science, though, so it depends on what level he is at.
Units are funny.
Fuel efficiency is measured in MPG or, more usefully, Litres per Kilometre. Litres per Kilometre can be rewritten as m3/m = m2. So fuel efficiency is measured in square metres.
Everything is relative.
Fuck. I need a drink.
It has an interpretation too. Imagine laying a tube of petrol behind you as you drive. The cross-section of that tube would be the square-metres given in the litres-per-metre cancellation.
I like the one for the efficiency of rocket engines. What you want to know is how much change in momentum you can extract per unit of fuel. You stick all the units of the stuff you're measuring (fuel mass, thrust, speed etc.) in and they cancel out leaving.... seconds. So the efficiency of rocket engines is measured in units of time.
Separate names with a comma.