An archer puts a .25kg arrow to the bowstring. An ave force of 196N is exerted to draw the string back 1.25m what speed does the arrow leave?
my brain is running in circles
my brain is running in circlesHelp please....
- Thread starter hellah10
- Start date
ohhh come on. i know someeeeee one knows how to do this....
you will be rewareded with many hoes and beer...(maybe) lool
you will be rewareded with many hoes and beer
...(maybe) lool
1.25 meter draw ? with a meter being what 39 inches?
that is almost a 49 inch draw ! IT DONT LEAVE THE BOW BREAKS !
that is almost a 49 inch draw ! IT DONT LEAVE THE BOW BREAKS !
just got back from my final....and this question was on the test....it was the only one i missed (i think)
(i think)Physics 101
Physics 101
Hey Hellah
I took physics 101 in 1972.
It was one of the hardest classes I took in undergraduate.
When all was said and done my class average from tests was about a 44. Once the bell curve was applied I came out with a
B+.
Truly a gift from God.
Hope you did as well or better than I did.
Happy Holidays
AzRusty
Randy
Physics 101
Hey Hellah
I took physics 101 in 1972.
It was one of the hardest classes I took in undergraduate.
When all was said and done my class average from tests was about a 44. Once the bell curve was applied I came out with a
B+.
Truly a gift from God.
Hope you did as well or better than I did.
Happy Holidays
AzRusty
Randy
My guess would be to use the old favorite Force = Mass x Acceleration. We know the mass (.25kg), we know the force (196N although I don't know what N represents actually), and we can determine velocity using Velocity = Acceleration x Time if we could figure out the Acceleration. That's the part I'm stuck on right now. Let's see, Distance = Velocity x Time, can we work that in since we know the distance (1.25M)? I can't figure out where to work out the Time part of the equations. Is that where the N variable comes into play?
I haven't had Physics since 1971.
I haven't had Physics since 1971.
N is the term for "Newtons".
Sorry hellah, did not get to open this thread till just now. Looks like another math geek got you the answer tho.
Its tough to do math problems on here, L* you can't show your work and its hard as hell to explain anything other than
"The Miracle Theory"
Sorry hellah, did not get to open this thread till just now. Looks like another math geek got you the answer tho.
Its tough to do math problems on here, L* you can't show your work and its hard as hell to explain anything other than
"The Miracle Theory"
I can't remember all the details from Physics (10 years ago and never used since), but you used an average force of 194 newtons to draw the bow 1.25 meters, so a combination of that (something like 194 * 1.25, but I forget the units) should represent the force being applied to the arrow fully drawn.
That will give you the force applied to the arrow, which you know the mass of, which you will accelerate for 1.25 meters starting from 0 m/s. If you know the acceleration and the distance you will accelerate something, you can calculate its velocity.
That might be way off, but I think it makes sense.
Of course this problem ignores all the stuff you need calculus for (non-constant acceleration, wind resistance, etc. etc.) but I think that's the gist of what the exam is getting at.
It seems like Koty'sDad mgiht be up on these things. You should have written "physics problem" in the header.
That will give you the force applied to the arrow, which you know the mass of, which you will accelerate for 1.25 meters starting from 0 m/s. If you know the acceleration and the distance you will accelerate something, you can calculate its velocity.
That might be way off, but I think it makes sense.
Of course this problem ignores all the stuff you need calculus for (non-constant acceleration, wind resistance, etc. etc.) but I think that's the gist of what the exam is getting at.
It seems like Koty'sDad mgiht be up on these things. You should have written "physics problem" in the header.
If you want to get technical about it, there is not enough info provided to solve this problem.
A. Are you using a compound bow? If so, there is a break-away point in which the bow reduces its strength to approx. half to help a person remain in the drawn position for an extended amount of time. You will need these two different force amounts.
B. Are you using a recurve bow? If so, it seems like one would need calculus to solve this problem, as a rate of change must be determined. The amount of pressure exerted by the bow is not a constant, and is greater the further the bow is drawn. Are we to assume the bow exerts a constant force?
A. Are you using a compound bow? If so, there is a break-away point in which the bow reduces its strength to approx. half to help a person remain in the drawn position for an extended amount of time. You will need these two different force amounts.
B. Are you using a recurve bow? If so, it seems like one would need calculus to solve this problem, as a rate of change must be determined. The amount of pressure exerted by the bow is not a constant, and is greater the further the bow is drawn. Are we to assume the bow exerts a constant force?
TheShrimp and Skinar are right and so is Stuman - you need to know an "efficiency" coefficient on the bow and what kind of bow you are using, but given that the problem doesnt state these variables then the Shrimp and Skinar have the right idea.
From the Force (N=newtons) and mass (kg) of the arrow, you can compute the acceleration from the equation F=ma. I dont recall what the units Newtons are comprised of so I dont know if F/m will directly give you acceleration in units of m/s squared. You may have to convert the units if it doesnt....As Shrimp said though, you know it will travel a distance of 1.25 meters before it leaves the bow, so from acceleration and distance you can figure out the velocity.
There is a basic equation that says v = v(0) + at.
Using calculus (which would be impossible to write out without a math equation editor since it uses integrals), you get the equation
v = v(0)^2 + 2as
where
v is the final velocity (in this case the velocity as it leaves the bow)
v(0) is the initial velocity (which I assumes has to be 0)
a = acceleration
s = distance = 1.25m
We need this equation since we dont know how long it takes the arrow to travel that initial 1.25 meters. The second equation only involves initial velocity, distance and acceleration...all of which we know or assume we know.
Since we know v(0), a, and s, you can plug the numbers in and compute v^2 and just take the square root to get v. I would plug the numbers in myself but the answer will be wrong if the units for acceleration arent right. I just cant remember what makes up Newtons.
Thanks for making me dust off 20 years worth of cobwebs out of my head on this one.
I love math, but I hated physics.
From the Force (N=newtons) and mass (kg) of the arrow, you can compute the acceleration from the equation F=ma. I dont recall what the units Newtons are comprised of so I dont know if F/m will directly give you acceleration in units of m/s squared. You may have to convert the units if it doesnt....As Shrimp said though, you know it will travel a distance of 1.25 meters before it leaves the bow, so from acceleration and distance you can figure out the velocity.
There is a basic equation that says v = v(0) + at.
Using calculus (which would be impossible to write out without a math equation editor since it uses integrals), you get the equation
v = v(0)^2 + 2as
where
v is the final velocity (in this case the velocity as it leaves the bow)
v(0) is the initial velocity (which I assumes has to be 0)
a = acceleration
s = distance = 1.25m
We need this equation since we dont know how long it takes the arrow to travel that initial 1.25 meters. The second equation only involves initial velocity, distance and acceleration...all of which we know or assume we know.
Since we know v(0), a, and s, you can plug the numbers in and compute v^2 and just take the square root to get v. I would plug the numbers in myself but the answer will be wrong if the units for acceleration arent right. I just cant remember what makes up Newtons.
Thanks for making me dust off 20 years worth of cobwebs out of my head on this one.
I love math, but I hated physics.
hellah10 said:
Naw, Skinar and Shrimp had the answer, I just filled in a few gaps here and there.
