Hovercraft B/C

[sciduck]

I hope nobody will be upset if I go?

What feats did Sir Christopher Cockerell achieve?

Uh (Click to Show Hidden Text)

He invented the hovercraft. Don't know what else he did...

[Zioly]

I hope nobody will be upset if I go?

What feats did Sir Christopher Cockerell achieve?

Uh (Click to Show Hidden Text)

He invented the hovercraft. Don't know what else he did...

Yeah, sorry about the easy question... I was tired. Anyways, he also was the first to theorize the "air cushion" part of the hovercraft, in which a momentum curtain would effectively prevent the leaking of additional air and trap air in the hovercraft's skirt. It's why almost all hovercrafts have skirts.

Your go!

[sciduck]

What are the world's largest hovercrafts used for?

[HandsFreeCookieDunk]

What are the world's largest hovercrafts used for?

I believe that would be the Zubr class, which is used for military transport.

[sciduck]

What are the world's largest hovercrafts used for?

I believe that would be the Zubr class, which is used for military transport.

Yup, your turn.

[HandsFreeCookieDunk]

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?

[sciduck]

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? (Click to Show Hidden Text)

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.

[HandsFreeCookieDunk]

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? (Click to Show Hidden Text)

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

[sciduck]

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? (Click to Show Hidden Text)

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.

[Zioly]

Do I show work? (Click to Show Hidden Text)

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 (Click to Show Hidden Text)

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.