Arrows and Physics!!

That's easy: the velocities add. As velocity is a vector quantity (it has both magnitude and direction) we can look at this as a simple one-dimensional problem (you didn't mention firing at any angle to horizontal....)

So fire forward: truck (60mph)+ arrow (150 mph)= total 210 mph

Backward: truck 60 mph +arrow (-150mph)=total -90 mph (note the minus sign in the answer, that means the arrow travels backwards.)

Now, if you fire upward at a 45 degree angle, on the moon so there is no air resistance, how far will each arrow travel? (Assume moon gravity is 1/6th of earth, because I am too lazy to look up the exact figure! )

 

yeah, funny and all but my uncle used to shoot clays in the outback... we'd be sitting in the pub (good ol aussie outback pub with corrugated iron roof) and hear BOOOM! then 30 seconds later a shower of lead. real nice.

 

Actually might be terminology - but in "Relativity" point of view from the truck.

1.) Forward (meaning facing the way the truck is going and firing) Truck going 60 MPH - Arrow travels 150. Would be 150 - 60 = Arrow would move forward at 90 mph, (not -90) - from the persons perspective on the truck.

2.) Backward (Meaning facing the back of the truck shooting away from the direction the truck is moving) the arrow would be traveling 210mph from the relative position of the person on the truck.

Now if you look at it from an observer’s relative position on the ground watching the archer shoot from the moving truck - the arrow is going 150 in both directions. (Assuming no air resistance).

 

physics depends on perspective entirely.

if it is from the perspective from a ground based observer, then the above posts are right. but if it is from the perspective of the shooter, it will be traveling at 150 mph (or whatever the figure was) at an angle of 0 or 180 off direction of travel (a velocity is a speed and a direction, that means you include both)

dubai vol: Vx = 106 [mph]. Ty = [pulls out physics notes] 82.2
Ty * Vx = 18084 [ft]


Jerrari: is there wind or not? or even air?

 

Since the arrow is already moving with the earth's rotation, and so are you, the earth's rotation doesn't factor into the equation.

 

Wrong, arrow would move 150 mph from the persons perspective on the truck.

Wrong, arrow would move 150 mph from the persons perspective on the truck.

Wrong again:
210 when shot forward
90 when shot rearword.

 

If there's one thing I learned about physics, it's that you have to use the correct terminology.

That's why the airplane physics thread made me want to kill myself.

 

And this is why I love Fchat. What other site requires you to contemplate physics/vectors/ and quantum logic?

No one has yet mentioned what happens at the atomic/quantum level at the tip of the arrow as it penetrates the time/space parallel...

 

True, and this question forgot to point out that the back yard has a conveyor in it which adds (or subtracts) from the arrows speed, depending on which way you are shooting it.....

 

What happened to terminal velocity? You know, drag against air of an object as a factor in it's motion.

 

Terminal velocity is relative to the force being applied as well as the aerodynamics of the object in motion. It's rather pointless to discuss here.


TEAK: Thanks for clearing up Mr. Wallace, I was about to unload but see you have it taken care of.

 

anyone want to try their hand at the question dubai vol brought up:
"Now, if you fire upward at a 45 degree angle, on the moon so there is no air resistance, how far will each arrow travel? "

to see if in my haste i did the calculations correct. i get 12782.1[ft] neglecting curvature of the moon. if you're ambitious Rmoon = 5708661.4 [ft]

actually i'm feeling ambitious, with curvature i get a distance of 12828.75 [ft]

anyone feel like confirming?



in my above post (#6) i really screwed up. it should be 155.5[ft/s] instead of 106[mph].
and therefore my multiplication was wrong so instead of 18084[ft], it should be the 12782.1 i have in this post
the teachers always say to watch your units, and see what happens when you dont.....the fchat guys think you're stupid or a satellite crashes into mars

 

man i got a great LOL from that.... thanks !!!


and i agree with you !!