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3 years ago

Describe two energy conversions that take place when you warm a cup of cocoa in a microwave oven.

2 answers:

7 0

1.)the microwaves are absorbed by the water molecules in the cocoa. this causes the water molecules to vibrate very fast.

2.)this fast vibration causes the molecules to heat themselves up by means of bumping into each other (friction).

baherus [9]3 years ago

4 0

Electrical energy -> wave energy (microwave)
wave energy -> potential/heat energy (cup of cocoa)

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Which of the following affects the speed of a seismic wave?

NemiM [27]

Answer:

The answer is B. composition

Explanation:

The speed of a seismic wave is governed by three interrelated factors, viz. the composition of the rock, pressure, and temperature.
Seismic waves travel at different speeds in different mediums.
This property of the seismic waves tends it to change the speed where the concentration of minerals in the rocks varies.
Other than that, the increasing temperature beneath the Earth's surface decreases the speed of the seismic waves, and the speed increases with increasing pressure as the waves go penetrating deep down into the Earth's interiors.

5 0

3 years ago

A car accelerates for 10 seconds. During this time, the angular

bagirrra123 [75]

Answer:

the angular acceleration of the car is 1.5 rad/s²

Explanation:

Given;

initial angular velocity, $\omega_i$ = 10 rad/s

final angular velocity, $\omega_f$ = 25 rad/s

time of motion, t = 10 s

The angular acceleration of the car is calculated as follows;

$a_r = \frac{\omega_f - \omega_i }{t} \\\\a_r = \frac{25-10}{10} = 1.5 \ rad/s^2$

Therefore, the angular acceleration of the car is 1.5 rad/s²

4 0

3 years ago

Use dimensional analysis to determine how the linear acceleration a in m/s2 of a particle traveling in a circle depends on some,

astraxan [27]

I have to say, i love this kind of problems.

So, we got the linear acceleration, as we all know, linear the acceleration its, in dimensional units:

$[a]=[\frac{distance}{time^2}]$ .

Now, we got the radius

$[r] = [distance]$

the angular frequency

$[\omega] = \frac{1}{s}$

and the mass

$[m]=[mass]$ .

Now, the acceleration doesn't have units of mass, so it can't depend on the mass of the particle.

The distance in the acceleration has exponent 1, and so does in the radius. As the radius its the only parameter that has units of distance, this means that the radius must appear with exponent 1. Lets write

$a \propto r$ .

The time in the acceleration has exponent -2 As the angular frequency its the only parameter that has units of time, this means that the angular frequency must appear, but, the angular frequency has an exponent of -1, this means it must be squared

$a \propto r \omega^2$ .

We are almost there. If this were any other problem, we would write:

$a = A r \omega^2$

where A its an dimensionless constant. Its common for this constants to appears if we need an conversion factor. If we wanted the acceleration in cm/s^2, for example. Luckily for us, the problem states that there is no dimensionless constant involved, so:

$a = r \omega^2$

5 0

3 years ago

A person struggles very hard to lift a large boulder. He puts in so much effort, he starts to sweat, his heart rate increases, a

Lesechka [4]

No, he did not perform any work. Work is when you’re using energy which results in a force. Even though he was tired and sweaty, he did not move the boulder. So therefore he did not perform any work.

5 0

4 years ago

Which city has already hosted the Olympic Games three times?

____ [38]

London, it has hosted the 1908, 1948 and the 2012 summer olympics

8 0

4 years ago

Read 2 more answers