All categories

4 years ago

What happens to dry ice when its temperature rises

1 answer:

8 0

Unlike the ice cubes in a cold drink , dry ice doesn't melt to become liquid at all. Instead, at room temperature, it changes directly from a solid to a gas a process called sublimation . This expansion causes a rapid temperature drop, and some of the carbon dioxide freezes into solid pellets of dry ice.

You might be interested in

Which of the following is a measurement of velocity?

Westkost [7]

Answer:

B) 55 m/h south

Explanation:

Velocity is the rate of displacement per unit of time.

It is mathematically expressed as:

Velocity = $\frac{displacement}{time}$

Displacement is the distance covered by a body in a specific direction.

Velocity is different from speed in that it specifies the direction of a body as it travels.

Therefore, we say, velocity is a scalar quantity.

When we are giving velocity values, the unit is expressed with the direction also delineated.

From the given choices, the unit with the south direction and meter per hour is obviously correct.

5 0

3 years ago

Find the shear stress and the thickness of the boundary layer (a) at the center and (b) at the trailing edge of a smooth flat pl

melomori [17]

Answer:

a) The shear stress is 0.012

b) The shear stress is 0.0082

c) The total friction drag is 0.329 lbf

Explanation:

Given by the problem:

Length y plate = 2 ft

Width y plate = 10 ft

p = density = 1.938 slug/ft³

v = kinematic viscosity = 1.217x10⁻⁵ft²/s

Absolute viscosity = 2.359x10⁻⁵lbfs/ft²

a) The Reynold number is equal to:

$Re=\frac{1*3}{1.217x10^{-5} } =246507, laminar$

The boundary layer thickness is equal to:

$\delta=\frac{4.91*1}{Re^{0.5} } =\frac{4.91*1}{246507^{0.5} } =0.0098$ ft

The shear stress is equal to:

$\tau=0.332(\frac{2.359x10^{-5}*3 }{1} )(246507)^{0.5} =0.012$

b) If the railing edge is 2 ft, the Reynold number is:

$Re=\frac{2*3}{1.215x10^{-5} } =493015.6,laminar$

The boundary layer is equal to:

$\delta=\frac{4.91*2}{493015.6^{0.5} } =0.000019ft$

The sear stress is equal to:

$\tau=0.332(\frac{2.359x10^{-5}*3 }{2} )(493015.6^{0.5} )=0.0082$

c) The drag coefficient is equal to:

$C=\frac{1.328}{\sqrt{Re} } =\frac{1.328}{\sqrt{493015.6} } ==0.0019$

The friction drag is equal to:

$F=Cp\frac{v^{2} }{2} wL=0.0019*1.938*(\frac{3^{2} }{2} )(10*2)=0.329lbf$

7 0

3 years ago

Please help!!!

aksik [14]

The answer is #3: Oxidation because oxidation is when a substance reacts with oxygen, which causes the substance to rust. When a rock contains iron and that iron comes in contact with oxygen, iron oxide is created; this weakens the rock.

3 0

3 years ago

Read 2 more answers

Hii:) I need help with qn 1 & please explain if possible too :) , thanks!

andrezito [222]

1. In the first 1.5 seconds, the lift accelerates from 0 to 3m/s. By definition, the acceleration is the ratio between the change in velocity and the time elapsed to change the velocity.

The change in velocity is $\Delta v = v_{\text{final}}-v_{\text{initial}}=3-0=3$ .

The time elapsed is 1.5 seconds, so the acceleration is

$a = \dfrac{3}{1.5}=2$

meters per second squared.

2. We know, from the previous point, that the lift travelled 20m from the first floor. Since it returns to the first floor after the ascent, it must travel again those same 20m, just in reverse (descending instead of ascending). So, the total distance travelled is $20+20=40$ meters.

The displacement, though, is zero, because it measures the distance between the starting and ending point of a certain motion. Since the lift starts and ends its motion at the same place (the first floor), its total displacement is zero.

3 0

3 years ago

Matter is anything that has mass and takes up space. Which units of measurement can you use to describe these two properties?

Papessa [141]

Answer: Matter is anything that has mass and takes up space . Mass is amount of mass that an object contains. Mass is measured by scale . Volume is amount of space that matter takes up .

Explanation:

4 0

3 years ago