Hovercraft B/C

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Re: Hovercraft B/C

Postby HandsFreeCookieDunk » February 27th, 2017, 6:13 am

I guess I'll go to the physics side.

A cylindrical water tank has a small hole in its side through which water is spurting. The hole is 5m above the ground and 1m below the surface of the water. For simplicity's sake, assume the water level in the tank is not dropping. How far horizontally does the water travel before hitting the ground?

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Re: Hovercraft B/C

Postby sciduck » February 27th, 2017, 7:18 am

I guess I'll go to the physics side.

A cylindrical water tank has a small hole in its side through which water is spurting. The hole is 5m above the ground and 1m below the surface of the water. For simplicity's sake, assume the water level in the tank is not dropping. How far horizontally does the water travel before hitting the ground?
Do I show work?
From Bernoulli's principle, I get a velocity of 4.427 m/s. Let's say that's horizontal velocity, so initial vertical velocity is 0 m/s. So it'll take 1.01015 s to hit the ground. No horizontal velocity --> 4.47 m. Uhhh, 1 sigfig? So ~4m.
Last edited by sciduck on February 27th, 2017, 12:05 pm, edited 2 times in total.
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Re: Hovercraft B/C

Postby HandsFreeCookieDunk » February 27th, 2017, 8:08 am

I guess I'll go to the physics side.

A cylindrical water tank has a small hole in its side through which water is spurting. The hole is 5m above the ground and 1m below the surface of the water. For simplicity's sake, assume the water level in the tank is not dropping. How far horizontally does the water travel before hitting the ground?
Do I show work?
From Bernoulli's principle, I get a velocity of 4.427 m/s. Let's say that's horizontal velocity, so initial vertical velocity is 0 m/s. So it'll take 1.01015 s to hit the ground. No horizontal velocity --> 4.6047 m. Uhhh, 1 sigfig? So ~5m.
Yeah, sorry about the sigfigs, I was just throwing numbers at it. I was with you until the final step, where x = vt = 4.427 m/s * 1.01015s = 4.472m

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Re: Hovercraft B/C

Postby sciduck » February 27th, 2017, 12:12 pm

I guess I'll go to the physics side.

A cylindrical water tank has a small hole in its side through which water is spurting. The hole is 5m above the ground and 1m below the surface of the water. For simplicity's sake, assume the water level in the tank is not dropping. How far horizontally does the water travel before hitting the ground?
Do I show work?
From Bernoulli's principle, I get a velocity of 4.427 m/s. Let's say that's horizontal velocity, so initial vertical velocity is 0 m/s. So it'll take 1.01015 s to hit the ground. No horizontal velocity --> 4.6047 m. Uhhh, 1 sigfig? So ~5m.
Yeah, sorry about the sigfigs, I was just throwing numbers at it. I was with you until the final step, where x = vt = 4.427 m/s * 1.01015s = 4.472m
Oops, I typed it in my calculator wrong ;a;

Next question: Say you are standing on top of a building and threw a ball A downward with a velocity -v, and threw a different ball B (from the same height) upward with a velocity of v. Then:
A) A will hit the ground with a velocity greater than B's.
B) B will hit the ground with a velocity greater than A's.
C) Both hit the ground at the same speed.
D) Neither of the balls will hit the ground.
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Re: Hovercraft B/C

Postby Zioly » March 1st, 2017, 3:14 pm

Do I show work?
From Bernoulli's principle, I get a velocity of 4.427 m/s. Let's say that's horizontal velocity, so initial vertical velocity is 0 m/s. So it'll take 1.01015 s to hit the ground. No horizontal velocity --> 4.6047 m. Uhhh, 1 sigfig? So ~5m.
Yeah, sorry about the sigfigs, I was just throwing numbers at it. I was with you until the final step, where x = vt = 4.427 m/s * 1.01015s = 4.472m
Oops, I typed it in my calculator wrong ;a;

Next question: Say you are standing on top of a building and threw a ball A downward with a velocity -v, and threw a different ball B (from the same height) upward with a velocity of v. Then:
A) A will hit the ground with a velocity greater than B's.
B) B will hit the ground with a velocity greater than A's.
C) Both hit the ground at the same speed.
D) Neither of the balls will hit the ground.
Answer
B will hit the ground with a velocity greater than A's, as B will attain a negative velocity, and thus head towards the ground, at a higher starting point than A. Thus, the extra distance needed to be traversed gives ball B a bit more time to accelerate due to gravity.
EDIT: hid the answer
EDIT 2: my answer's wrong. I had a brainfart when I mistook ball A's initial velocity as a simple drop and therefore 0 m/s. HandsFreeCookieDunk's explanation with the energies allowed me to realize my mistake. Sorry 'bout that.
Last edited by Zioly on March 1st, 2017, 8:56 pm, edited 1 time in total.
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Re: Hovercraft B/C

Postby HandsFreeCookieDunk » March 1st, 2017, 6:39 pm

Do I show work?
From Bernoulli's principle, I get a velocity of 4.427 m/s. Let's say that's horizontal velocity, so initial vertical velocity is 0 m/s. So it'll take 1.01015 s to hit the ground. No horizontal velocity --> 4.6047 m. Uhhh, 1 sigfig? So ~5m.
Yeah, sorry about the sigfigs, I was just throwing numbers at it. I was with you until the final step, where x = vt = 4.427 m/s * 1.01015s = 4.472m
Oops, I typed it in my calculator wrong ;a;

Next question: Say you are standing on top of a building and threw a ball A downward with a velocity -v, and threw a different ball B (from the same height) upward with a velocity of v. Then:
A) A will hit the ground with a velocity greater than B's.
B) B will hit the ground with a velocity greater than A's.
C) Both hit the ground at the same speed.
D) Neither of the balls will hit the ground.
Answer
The answer is C. Because the two balls have the same initial total energy (gravitational potential+kinetic) they will have the same kinetic energy when gravitational potential energy is 0 and will therefore have the same velocity. Lol at answer D though. :lol:
Last edited by HandsFreeCookieDunk on March 1st, 2017, 8:28 pm, edited 1 time in total.

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Re: Hovercraft B/C

Postby Ashernoel » March 1st, 2017, 7:21 pm

Do I show work?
From Bernoulli's principle, I get a velocity of 4.427 m/s. Let's say that's horizontal velocity, so initial vertical velocity is 0 m/s. So it'll take 1.01015 s to hit the ground. No horizontal velocity --> 4.6047 m. Uhhh, 1 sigfig? So ~5m.
Yeah, sorry about the sigfigs, I was just throwing numbers at it. I was with you until the final step, where x = vt = 4.427 m/s * 1.01015s = 4.472m
Oops, I typed it in my calculator wrong ;a;

Next question: Say you are standing on top of a building and threw a ball A downward with a velocity -v, and threw a different ball B (from the same height) upward with a velocity of v. Then:
A) A will hit the ground with a velocity greater than B's.
B) B will hit the ground with a velocity greater than A's.
C) Both hit the ground at the same speed.
D) Neither of the balls will hit the ground.
Answer
Answer: C. Velocity is a vector, and by throwing A down with -v, it can be translated to upward with v, the same as B. then due to acceleration due to gravity, both will follow the same trajectory and hit the ground at the same time
Last edited by Ashernoel on March 1st, 2017, 9:00 pm, edited 2 times in total.
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Re: Hovercraft B/C

Postby kenniky » March 1st, 2017, 7:38 pm


Yeah, sorry about the sigfigs, I was just throwing numbers at it. I was with you until the final step, where x = vt = 4.427 m/s * 1.01015s = 4.472m
Oops, I typed it in my calculator wrong ;a;

Next question: Say you are standing on top of a building and threw a ball A downward with a velocity -v, and threw a different ball B (from the same height) upward with a velocity of v. Then:
A) A will hit the ground with a velocity greater than B's.
B) B will hit the ground with a velocity greater than A's.
C) Both hit the ground at the same speed.
D) Neither of the balls will hit the ground.
title
C. Velocity is a vector, and by throwing A down with -v, it can be translated to upward with v, the same as B. then due to acceleration due to gravity, both will follow the same trajectory and hit the ground at the same time
You gotta have a title to your [ hide] lol

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Re: Hovercraft B/C

Postby Ashernoel » March 1st, 2017, 9:01 pm

title
thanks for the help, this is pretty sick :p
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Re: Hovercraft B/C

Postby sciduck » March 3rd, 2017, 5:37 pm


Yeah, sorry about the sigfigs, I was just throwing numbers at it. I was with you until the final step, where x = vt = 4.427 m/s * 1.01015s = 4.472m
Oops, I typed it in my calculator wrong ;a;

Next question: Say you are standing on top of a building and threw a ball A downward with a velocity -v, and threw a different ball B (from the same height) upward with a velocity of v. Then:
A) A will hit the ground with a velocity greater than B's.
B) B will hit the ground with a velocity greater than A's.
C) Both hit the ground at the same speed.
D) Neither of the balls will hit the ground.
Answer
The answer is C. Because the two balls have the same initial total energy (gravitational potential+kinetic) they will have the same kinetic energy when gravitational potential energy is 0 and will therefore have the same velocity. Lol at answer D though. :lol:
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Re: Hovercraft B/C

Postby HandsFreeCookieDunk » March 4th, 2017, 8:07 pm

Shamelessly copied from the internet....

According to the Guinness Book of World Records, the fastest recorded baseball pitch was delivered by Nolan Ryan in 1974. The pitch was clocked at 100.9 mi/hr (45.0 m/s). Determine the impulse required to give a 0.145-kg baseball such a momentum.

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Re: Hovercraft B/C

Postby Zioly » March 5th, 2017, 9:31 am

Shamelessly copied from the internet....

According to the Guinness Book of World Records, the fastest recorded baseball pitch was delivered by Nolan Ryan in 1974. The pitch was clocked at 100.9 mi/hr (45.0 m/s). Determine the impulse required to give a 0.145-kg baseball such a momentum.
Answer
Impulse is known as the change in momentum over time. The impulse-momentum theory states that J=Δp. So, J=(0.145 kg*45 m/s)-(0.145 kg*0 m/s) J=6.525 kg*m/s - 0 kg*m/s J=6.525N - 0N J=6.525N
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Re: Hovercraft B/C

Postby HandsFreeCookieDunk » March 5th, 2017, 9:52 am

Shamelessly copied from the internet....

According to the Guinness Book of World Records, the fastest recorded baseball pitch was delivered by Nolan Ryan in 1974. The pitch was clocked at 100.9 mi/hr (45.0 m/s). Determine the impulse required to give a 0.145-kg baseball such a momentum.
Answer
Impulse is known as the change in momentum over time. The impulse-momentum theory states that J=Δp. So, J=(0.145 kg*45 m/s)-(0.145 kg*0 m/s) J=6.525 kg*m/s - 0 kg*m/s J=6.525N - 0N J=6.525N
So close
The units of impulse are N*s.

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Re: Hovercraft B/C

Postby Zioly » March 5th, 2017, 9:59 am

Shamelessly copied from the internet....

According to the Guinness Book of World Records, the fastest recorded baseball pitch was delivered by Nolan Ryan in 1974. The pitch was clocked at 100.9 mi/hr (45.0 m/s). Determine the impulse required to give a 0.145-kg baseball such a momentum.
Answer
Impulse is known as the change in momentum over time. The impulse-momentum theory states that J=Δp. So, J=(0.145 kg*45 m/s)-(0.145 kg*0 m/s) J=6.525 kg*m/s - 0 kg*m/s J=6.525N - 0N J=6.525N
So close
The units of impulse are N*s.
Sorry about that, but wouldn't it be N/s? Also, what unit is momentum in? I had a question on a test the other day and was uncertain... as you can tell, impulse and momentum are concepts I'm not as familiar with. :)
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Mousetrap Vehicle Hovercraft Ecology Experimental Design (or other inquiry :P) ...Yes, my profile picture is G2 apEX at the PGL Major Qual. :lol:

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Re: Hovercraft B/C

Postby HandsFreeCookieDunk » March 5th, 2017, 10:27 am

Answer
Impulse is known as the change in momentum over time. The impulse-momentum theory states that J=Δp. So, J=(0.145 kg*45 m/s)-(0.145 kg*0 m/s) J=6.525 kg*m/s - 0 kg*m/s J=6.525N - 0N J=6.525N
So close
The units of impulse are N*s.
Sorry about that, but wouldn't it be N/s? Also, what unit is momentum in? I had a question on a test the other day and was uncertain... as you can tell, impulse and momentum are concepts I'm not as familiar with. :)
No, it's N*s. As you said, the unit of momentum is kg*m/s. Since Impulse is the change in momentum, it will have the same unit. A Newton is kg*m/s^2. Therefore, the unit for momentum is the Newton times a unit of time.


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