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4 years ago

Complete the sentences to describe the convection experiment.

Physics

2 answers:

rodikova [14]4 years ago

6 0

Answer: red water in hot water

Rose to the top of the beaker

Warmer than

Explanation:

riadik2000 [5.3K]4 years ago

4 0

Answer:

The heat transfer model showed convection.

In the convection model, the red water on the bottom of the beaker is hot

This means that the water at the bottom of the beaker was less dense than the water near the top of the beaker.

Explanation:

Convection is the transference of heat energy by the movement (translation) of the particles of fluid (liquids or gases).

When the water on the bottom of the beaker is heated, it expands and becomes less dense.

The water near the top of the beaker is cold which makes it denser than the water at the bottom of the beaker.

Thus, the hot water from the bottom of the beaker will ascend toward the top of the beaker, while the cold water on top will descend toward the bottom. As long, as there is a difference of temperature between the water on the bottom and on top of the beaker, there will be a continuous movement of the particles: cold particles from the top replace hot particles from the bottom that ascend, and when the cold particles are heated they will ascend and will be replaced by new cold particles. This continuous translation of hot and cold particles in fluids is the model of heat transfer by convection.

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(a) what is the acceleration of two falling sky divers (mass 132 kg including parachute) when the upward force of air resistance

Komok [63]

As per the question the mass of two falling sky drivers is 132 kg.

First we have to calculate their acceleration.

Whenever a body falls freely under gravity,its acceleration is acceleration due to gravity i.e g whose value is 9.8 m/s^2.

The earth pulls the object with a force equal to the weight of the body.

Hence the force gravity F=W= mg [ here m is mass of the body]

Here m =132 kg.

Hence force of gravity F= mg

=132 kg ×9.8 m/s^2

=1293.6 kg m/s^2

=1293.6 N [ here N[newton] is the unit of force.]

As per the question the air resistance is one fourth of weight of the bodies.

Hence air resistance F' =1/4 mg

$=\frac{1}{4} *1293.6N$

$=323.4 N$

Here F acts in vertically downward direction while F' acts in vertically upward direction.

Hence the net force acting on the particle is F-F'.

$F_{net} =1293.6N -323.4N$

$=970.2 N$

From Newton's second law of motion we know that net force is the product of mass and acceleration i.e

$F_{net} =ma$ [Here a is the acceleration]

$a =\frac{F_{net} }{m}$

$= \frac{970.2}{132} m/s^2$

$=7.35 m/s^2$

In the second question it has been told that they descend with uniform speed.hence acceleration of the two bodies will be zero.

we know that F= ma

=m×0

=0 N

Hence they will not get any force when they will descend with a uniform speed.

4 0

3 years ago

A dime is placed in front of a concave mirror that has a radius of curvature R = 0.40 m. The image of the dime is inverted and t

andrew11 [14]

Answer:

distance between the dime and the mirror, u = 0.30 m

Given:

Radius of curvature, r = 0.40 m

magnification, m = - 2 (since,inverted image)

Solution:

Focal length is half the radius of curvature, f = $\frac{r}{2}$

f = $\frac{0.40}{2} = 0.20 m$

Now,

m = - $\frac{v}{u}$

- 2 = - $\frac{v}{u}$

$\frac{v}{u}$ = 2 (2)

Now, by lens maker formula:

$\frac{1}{f} = \frac{1}{u} + \frac{1}{v}$

$\frac{1}{v} = \frac{1}{f} - \frac{1}{u}$

v = $\frac{uf}{u - f}$ (3)

From eqn (2):

v = 2u

put v = 2u in eqn (3):

2u = $\frac{uf}{u - f}$

2 = $\frac{f}{u - f}$

2(u - 0.20) = 0.20

u = 0.30 m

6 0

3 years ago

What is the lowest gauge pressure that the average person can achieve inside his lungs? express your answer with the appropriate

eimsori [14]

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4 years ago

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Elza [17]

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7 0

3 years ago

How to determine whether the object is magnetic.

o-na [289]

Answer:

By holding another magnet close to it. If the object is attracted to the magnet, then it too is magnetic.

7 0

3 years ago

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