Things you always wanted to know the answer to [Vol. 3]
Discussion
SpeckledJim said:
A hovering rocket is doing the same work in a downdraft as a climbing rocket.
What am I missing?
Pretty much everything.What am I missing?
Yes the air resistance would be the same.
But the work done against gravity is completely different.
When you hover you do no work. (With zero air resistance.)
When you climb you do work. (With zero air resistance.)
http://www.batesville.k12.in.us/physics/phynet/mec...
"Work is not always force x distance, but work always involves motion of some sort. No distance - no work."
RobinOakapple said:
SpeckledJim said:
I'm dying to be proven wrong, but I'm pretty sure Newton is with me.
Moving mass against gravity requires more energy than simply resisting it.Standing still on a staircase means that you are resisting gravity, but requires less energy that walking up the staircase.
Gravity applies a fixed force against a body. Doesn't matter what that body is doing, the force of gravity is a constant (for the purposes of this question
).It also requires a fixed force to make an object accelerate by a fixed amount. (newton's second)
Now, whether that acceleration is from -2mph to 0mph, or from 0mph to 2mph is immaterial. The force is the same.
Is there anyone out there in webworld who agrees with me?
SpeckledJim said:
RobinOakapple said:
SpeckledJim said:
I'm dying to be proven wrong, but I'm pretty sure Newton is with me.
Moving mass against gravity requires more energy than simply resisting it.Standing still on a staircase means that you are resisting gravity, but requires less energy that walking up the staircase.
Gravity applies a fixed force against a body. Doesn't matter what that body is doing, the force of gravity is a constant (for the purposes of this question
).It also requires a fixed force to make an object accelerate by a fixed amount. (newton's second)
Now, whether that acceleration is from -2mph to 0mph, or from 0mph to 2mph is immaterial. The force is the same.
Is there anyone out there in webworld who agrees with me?
SpeckledJim said:
Gravity applies a fixed force against a body. Doesn't matter what that body is doing, the force of gravity is a constant (for the purposes of this question ).
A fixed force is required to make an object accelerate by a fixed amount. (newton's second)
Now, whether that acceleration is from -2mph to 0mph, or from 0mph to 2mph is immaterial. The force is the same.
Can you tell me why this is wrong?).A fixed force is required to make an object accelerate by a fixed amount. (newton's second)
Now, whether that acceleration is from -2mph to 0mph, or from 0mph to 2mph is immaterial. The force is the same.
RobinOakapple said:
Part of the reason for starting this thread was that I have been considering getting an exercise machine and I'm trying to make sure I understand the physics principles involved. I'd like something that emulated the effort of walking upstairs.
Many treadmills can be adjusted to slope upwards. and take it from me it's much harder work than horizontal. The reason has nothing to do with increasing potential energy and classical physics weight x height. When you walk or run, much of the work you do is accelerating then decelerating your thighs and shins each step. Both require muscles to contract. Uphill on a treadmill requires you to lift your knees higher and stretch the downhill leg further.
Some of the arguments here would be only be true if we had wheels, not legs.
Nimby said:
When you walk or run, much of the work you do is accelerating then decelerating your thighs and shins each step. Both require muscles to contract. Uphill on a treadmill requires you to lift your knees higher and stretch the downhill leg further.
All of that may well be true, but it's not what the discussion is about. AIUI, the question is not so much whether walking up a down escalator or on a sloping treadmill, is hard work so much as whether actually walking upstairs or up an actual slope is harder, and if so by how much.
SpeckledJim said:
SpeckledJim said:
Gravity applies a fixed force against a body. Doesn't matter what that body is doing, the force of gravity is a constant (for the purposes of this question ).
A fixed force is required to make an object accelerate by a fixed amount. (newton's second)
Now, whether that acceleration is from -2mph to 0mph, or from 0mph to 2mph is immaterial. The force is the same.
Can you tell me why this is wrong?).A fixed force is required to make an object accelerate by a fixed amount. (newton's second)
Now, whether that acceleration is from -2mph to 0mph, or from 0mph to 2mph is immaterial. The force is the same.
But you are still ignoring gravity.
On a billiard table the force to get the ball to 2mph is the same as that which is needed to keep the ball stationary on a 2mph conveyor belt (woohoo!).
That's all well and good.
But now imagine a sloping billiard table (no conveyor belt).
Applying the same force will get it to head off at 2mph which rapidly slows to 0mph and then it comes back, eventually hitting the start point at roughly -2mph again.
To keep the ball going at a constant 2mph on a sloped billiard table would require A CONSTANT FORCE.
Not a one off.
How do you maximize acceleration?
If you had a hypothetical car filled with helium so it had very little weight on the wheels and 100HP engine it would wheelspin to get up to speed.
But if you had a car filled with lead and 100HP engine, there would be no wheelslip, but due to the weight it would take a long time to accelerate that weight.
So there must be a 'sweet spot' of weight on the wheels for optimal acceleration. So is it just a function of the coefficient of friction the tyres have with the road? Like is a dragster the optimum weight? Or are they always looking to lighten the car? And is there a point (for 0-60) on a car where the only way to increase acceleration times is to add weight rather than power?
If you had a hypothetical car filled with helium so it had very little weight on the wheels and 100HP engine it would wheelspin to get up to speed.
But if you had a car filled with lead and 100HP engine, there would be no wheelslip, but due to the weight it would take a long time to accelerate that weight.
So there must be a 'sweet spot' of weight on the wheels for optimal acceleration. So is it just a function of the coefficient of friction the tyres have with the road? Like is a dragster the optimum weight? Or are they always looking to lighten the car? And is there a point (for 0-60) on a car where the only way to increase acceleration times is to add weight rather than power?
Brother D said:
How do you maximize acceleration?
If you had a hypothetical car filled with helium so it had very little weight on the wheels and 100HP engine it would wheelspin to get up to speed.
But if you had a car filled with lead and 100HP engine, there would be no wheelslip, but due to the weight it would take a long time to accelerate that weight.
So there must be a 'sweet spot' of weight on the wheels for optimal acceleration. So is it just a function of the coefficient of friction the tyres have with the road? Like is a dragster the optimum weight? Or are they always looking to lighten the car? And is there a point (for 0-60) on a car where the only way to increase acceleration times is to add weight rather than power?
Best Solution is as light as possible, with weight transfer due to acceleration moving all of that weight to the driven wheels.If you had a hypothetical car filled with helium so it had very little weight on the wheels and 100HP engine it would wheelspin to get up to speed.
But if you had a car filled with lead and 100HP engine, there would be no wheelslip, but due to the weight it would take a long time to accelerate that weight.
So there must be a 'sweet spot' of weight on the wheels for optimal acceleration. So is it just a function of the coefficient of friction the tyres have with the road? Like is a dragster the optimum weight? Or are they always looking to lighten the car? And is there a point (for 0-60) on a car where the only way to increase acceleration times is to add weight rather than power?
I may have asked this before and got no answer.
Was on a river cruise, the man doing the commentary said Canada geese are now officially classed as a pest. Millions of them, taking over the Thames and other rivers.
So why don't we eat them. They look quite plump and tasty. It can't be that expensive to round them up and slaughter them. Or how about eating the eggs? Seems like a missed opportunity.
Was on a river cruise, the man doing the commentary said Canada geese are now officially classed as a pest. Millions of them, taking over the Thames and other rivers.
So why don't we eat them. They look quite plump and tasty. It can't be that expensive to round them up and slaughter them. Or how about eating the eggs? Seems like a missed opportunity.
TwigtheWonderkid said:
I may have asked this before and got no answer.
Was on a river cruise, the man doing the commentary said Canada geese are now officially classed as a pest. Millions of them, taking over the Thames and other rivers.
So why don't we eat them. They look quite plump and tasty. It can't be that expensive to round them up and slaughter them. Or how about eating the eggs? Seems like a missed opportunity.
They're wild birds, not game birds, and protected by law. https://www.gov.uk/guidance/wild-birds-protection-...Was on a river cruise, the man doing the commentary said Canada geese are now officially classed as a pest. Millions of them, taking over the Thames and other rivers.
So why don't we eat them. They look quite plump and tasty. It can't be that expensive to round them up and slaughter them. Or how about eating the eggs? Seems like a missed opportunity.
It's illegal to sell them or anything made from them. http://www.dailymail.co.uk/femail/article-2022964/...
TwigtheWonderkid said:
I may have asked this before and got no answer.
Was on a river cruise, the man doing the commentary said Canada geese are now officially classed as a pest. Millions of them, taking over the Thames and other rivers.
So why don't we eat them. They look quite plump and tasty. It can't be that expensive to round them up and slaughter them. Or how about eating the eggs? Seems like a missed opportunity.
The best recipe for cooking a Canada goose is to soak a house brick in red wine, stuff the bird with the brick and slowly roast it in an oven. You then throw away the goose and eat the brick. Was on a river cruise, the man doing the commentary said Canada geese are now officially classed as a pest. Millions of them, taking over the Thames and other rivers.
So why don't we eat them. They look quite plump and tasty. It can't be that expensive to round them up and slaughter them. Or how about eating the eggs? Seems like a missed opportunity.
TwigtheWonderkid said:
I may have asked this before and got no answer.
Was on a river cruise, the man doing the commentary said Canada geese are now officially classed as a pest. Millions of them, taking over the Thames and other rivers.
So why don't we eat them. They look quite plump and tasty. It can't be that expensive to round them up and slaughter them. Or how about eating the eggs? Seems like a missed opportunity.
Can be shot and eaten but not sold apparentlyWas on a river cruise, the man doing the commentary said Canada geese are now officially classed as a pest. Millions of them, taking over the Thames and other rivers.
So why don't we eat them. They look quite plump and tasty. It can't be that expensive to round them up and slaughter them. Or how about eating the eggs? Seems like a missed opportunity.
kers. Gassing Station | The Lounge | Top of Page | What's New | My Stuff