Gravity

[grub]

hiya all, grub here: first time poster, long time lifter.

Normally when it comes to pumping iron i don't have any problems. But today in class i was confronted with a new concept that worried me somewhat: the strength of a gravitational force is proportional to the distance between two particular objects. Does this mean that as i lift a weight, it becomes easier and easier to lift? This seems rather counter intuitive considering i dont FEEL any change in weight.

all in all i was wondering if anyone could confirm this, and whether or not anyone had any ideas as to how i could stop weight getting lighter as i lift them.

help much appreciated

-grub

[availn]

...

It gets lighter, but only by a very insignificant amount, probably not measurable. There's no way to stop this from happening, but you shouldn't worry, it doesn't impact your exercise at all, just keep lifting.

[TheFedExpress]

Yeah in 3/4 Physics we learnt the equation for gravitational force, in honour of pi I have refused to remember, however I do know that as you lift a weight, it would take you many decimal places to find any differences!

[grub]

...

It gets lighter, but only by a very insignificant amount, probably not measurable. There's no way to stop this from happening, but you shouldn't worry, it doesn't impact your exercise at all, just keep lifting.

im very careful when it comes to being sure im doing a full workout. I really want to try to avoid any half arsery that may result from this gravitational conundrum. if anyone has any solution to my problem pls dont' hesitate to let me know.

PS i would also like to know how much workout ive missed out on a result of gravity's diminishing field. lets say for instance that i have done 3x5 sets of BB press once a week for the last 30 weeks using a weight of 80kg. how much work (as in work done) have i not done as a result of newton's law of universal gravitation? i would appreciate a solution so that i can start cramming in the extra sets to make up.

-grub

[dhua]

if you lift the weights in water it cansels out the gravity i read it somewhere on the internet

[Hancock]

im very careful when it comes to being sure im doing a full workout. I really want to try to avoid any half arsery that may result from this gravitational conundrum. if anyone has any solution to my problem pls dont' hesitate to let me know.

PS i would also like to know how much workout ive missed out on a result of gravity's diminishing field. lets say for instance that i have done 3x5 sets of BB press once a week for the last 30 weeks using a weight of 80kg. how much work (as in work done) have i not done as a result of newton's law of universal gravitation? i would appreciate a solution so that i can start cramming in the extra sets to make up.

-grub

You know that the constant G is equal to yeah? That number is so small that any discernable difference in the gravitational weight force is going to be of nano (10^-9) or smaller (I'm just estimating). You'd probably make up the loss of work by doing one extra rep.

TLDR; don't worry about it too much. The effect is tiny.

[cesc]

yeah man it's pretty small so you say you been concerend about how many reps you have to do to make up, well. If you just do 2 extra reps, you'll make up for that particular set and make up for past ones you missed!

-cesc

[Robert123]

Don't worry about doing an extra rep, you will probably injury yourself or ruin your form. The affect shouldn't be worries about. This is because we are already aprox 6000km from the centre of the earth, an extra 10cm would have a practically a zero affect due to the much larger numbers use in the formula to calculate it.

[thushan]

hiya all, grub here: first time poster, long time lifter.

Normally when it comes to pumping iron i don't have any problems. But today in class i was confronted with a new concept that worried me somewhat: the strength of a gravitational force is proportional to the distance between two particular objects. Does this mean that as i lift a weight, it becomes easier and easier to lift? This seems rather counter intuitive considering i dont FEEL any change in weight.

all in all i was wondering if anyone could confirm this, and whether or not anyone had any ideas as to how i could stop weight getting lighter as i lift them.

help much appreciated

-grub

You're right. However, the distance you lift your weight is INSIGNIFICANT compared to the distance of the weight from the centre of the Earth (where the centre of mass is deemed to be). The radius of the earth is about 6000 km = 6,000,000 metres. When you lift your weight say 0.60 metres up (for a bicep curl), you're changing the distance from say 6,000,000 to 6,000,000.6 metres - this is a 0.0001% difference. Given F = GMm/r^2, F would only vary by 0.02%. In other words, say you're lifting 10 kg (100 N) (at ground level). When you lift it 60 cm, the gravitational force will be 99.99998 N - equivalent of 9.999998 kg. Negligible.