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3 years ago

In a thermos bottle, the vacuum between two glass bottles prevents heat being conducted between the bottles. T or F

Physics

2 answers:

alisha [4.7K]3 years ago

7 0

Fouls hop that helped(:(:(:(:

Gala2k [10]3 years ago

5 0

the answer is true because do your own experiment..for example: if the inside of your home is warmer than the outside/ smoking a cigarette by an open window wen it's cold outside, you will notice the cigarette smoke comes back inside, that is because doing this creates the opposite wanted effect. the temperature difference from inside -outside causes the cold air to b drawn to the warmer air therefore creating this effect. similar to lower concentrations moving to higher concentrations with h2o..hope this helps, unless I misunderstood??

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Which process is most responsible for the increase in early earth's atmospheric oxygen levels

sammy [17]

It is photosynthesis

4 0

3 years ago

A 5.0 kg block of ice is at rest at the top of a smooth inclined plane. The block is released and slides 2.0 m down the plane. A

harkovskaia [24]

Answer:

a) 98.1 Joules

b) 49.05 N × sin(θ)

c) 9.81 × sin(θ)

d) The velocity of the block at the bottom of the plane, v is approximately 6.264 m/s

e) 98.1 Joules

Explanation:

The given parameters of the block are;

The mass of the block, m = 5.0 kg

The distance down the plane the block slides, h = 2.0 m

The friction between the block and the surface = 0

Let θ represent the angle of inclination oof the plane

a) The gravitational potential energy, P.E. = m·g·h

Where;

g = The acceleration due to gravity ≈ 9.81 m/s²

∴ P.E. ≈ 5.0 kg × 9.81 m/s² × 2.0 m = 98.1 Joules

The gravitational potential energy, P.E. ≈ 98.1 Joules

b) The component of the weight of the block parallel to the plane, $w_{\parallel}$ , is given as follows;

$w_{\parallel}$ = w × sin(θ) = m·g·sin(θ)

∴ $w_{\parallel}$ ≈ 5.0 kg × 9.81 m/s² × sin(θ) = 49.05 × sin(θ) N

The component of the weight of the block parallel to the plane, $w_{\parallel}$ ≈ 49.05 N × sin(θ)

c) The component of the weight along the inclined plane = The force with which the block moves along the inclined plane, therefore;

$w_{\parallel}$ = m·g·sin(θ) = m·a

Where <em>a</em> represents the acceleration of the block along the plane

Therefore, by comparison, we have;

g·sin(θ) = a

∴ a ≈ 9.81 × sin(θ)

d) Given that the motion of the block is 2.0 m downwards, we have;

The velocity of the block at the bottom of the plane, v² = 2·g·h

Therefore, v² ≈ 2 × 9.81 m/s²× 2.0 m = 39.24 m²/s²

v = √(39.24 m²/s²) ≈ 6.264 m/s

e) The kinetic energy at the bottom of the plane, K.E. = (1/2)·m·v²

∴ K.E. = (1/2) × 5.0 kg × 39.24 m²/s² = 98.1 J

7 0

3 years ago

The process of converting energy produced by wind turbines into electricity is about 40 percent efficient. If the transport of e

ExtremeBDS [4]

Answer: 7.2%

Explanation:

Given

Efficiency of converting energy produced by wind into electricity is about $\eta_1=40\%$

Transport of electricity efficiency $\eta_2=90\%$

Fluorescent light bulb efficiency is $\eta_3=20\%$

Overall efficiency is the product of all the efficiencies i.e.

$\Rightarrow \eta=\eta_1\times \eta_2\times \eta_3\\\\\Rightarrow \eta=0.4\times 0.9\times 0.2\\\Rightarrow \eta=0.072\ \text{or}\ 7.2\%$

Therefore, the overall efficiency is 7.2%

7 0

3 years ago

A particle is acted on by two torques about the origin: τ→1 has a magnitude of 8 N·m and is directed in the positive direction o

lyudmila [28]

To give solution to the exercise we must use the concepts of Torque, Vector magnitude and vector direction of the forces.

For the given problem we have to

$T_i = 8Nm$

$T_j = -8.9Nm$

In this way the torque acting on the particle as a function of distance and time is,

$\tau = \frac{dL}{dt} = 8\hat{i}-8.9\hat{j}$

The net torque acting on the particle is

$\tau_{net} = \sqrt{T_i^2+T_j^2}$

$\tau_{net} = \sqrt{(8)^2+(-8.9)^2}$

$\tau_{net} = 11.967Nm$

PART B) The direction of the torque is given by,

$tan\theta = \frac{y}{x}$

$\theta = tan^{-1}\frac{y}{x}$

$\theta = tan^{-1}(\frac{-8.9}{8})$

$\theta = -48.04\°$

Therefore the torque direction is 48.04° below the x axis.

5 0

4 years ago

At which points would the river be traveling the slowest?

Vesnalui [34]

Answer:

This would be traveling at the lower reaches.

Explanation:

A river would be traveling the fastest at the upper reaches and it becomes slower at the middle reaches and the slowest at the lower reaches. A place where water flows fast in a river is where the width is narrow and the bottom is steep. (This is just examples incase you would like to keep notes).

4 0

3 years ago