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2 years ago

Which of the following is the best definition of a closed system?

Physics

1 answer:

lisov135 [29]2 years ago

4 0

The answer is either

b A system in which Newton's Laws are valid

c A system in which there are no external forces.

Explanation:

not a, and not d

There are energy changes in a closed system.

A closed system obeys the conservation laws in its physical description.

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What does it mean if the slope is zero?

kiruha [24]

The object is not moving.

My explanation is that say if you sit a ball on the table and it is a smooth surface with no bumps or anything. The ball will sit still since it can’t roll unless you hit it.

Hope this helps!

5 0

2 years ago

A uniform rod of mass 3.30×10−2 kg and length 0.450 m rotates in a horizontal plane about a fixed axis through its center and pe

Alex73 [517]

(a) 2.75 rev/min

The moment of inertia of the rod rotating about its center is:

$I_R=\frac{1}{12}ML^2$

where

$M=3.30\cdot 10^{-2} kg$ is its mass

L = 0.450 m is its length

Substituting,

$I_R=\frac{1}{12}(3.30\cdot 10^{-2})(0.450)^2=5.57\cdot 10^{-4} kg m^2$

The moment of inertia of the two rings at the beginning is

$I_r = 2mr^2$

where

m = 0.200 kg is the mass of each ring

$r=5.20\cdot 10^{-2} m$ is their distance from the center of the rod

Substituting,

$I_r=2(0.200)(5.20\cdot 10^{-2})^2=1.08\cdot 10^{-3} kg m^2$

So the total moment of inertia at the beginning is

$I_1=I_R+I_r = 5.57\cdot 10^{-4}+1.08\cdot 10^{-3}=1.64\cdot 10^{-3}kg m^2$

The initial angular velocity of the system is

$\omega_1 = 35.0 rev/min$

The angular momentum must be conserved, so we can write:

$L=I_1 \omega_1 = I_2 \omega_2$ (1)

where $I_2$ is the moment of inertia when the rings reach the end of the rod; in this case, the distance of the ring from the center is

$r=\frac{0.450 m}{2}=0.225 m$

so the moment of inertia of the rings is

$I_r=2(0.200)(0.225)^2=0.0203 kg m^2$

and the total moment of inertia is

$I_2 = I_R + I_r =5.57\cdot 10^{-4} + 0.0203 = 0.0209 kg m^2$

Substituting into (1), we find the final angular speed:

$\omega_2 = \frac{I_1 \omega_1}{I_2}=\frac{(1.64\cdot 10^{-3})(35.0)}{0.0209}=2.75 rev/min$

(b) 103.0 rev/min

When the rings leave the rod, the total moment of inertia is just equal to the moment of inertia of the rod, so:

$I_2 = I_R = 5.57\cdot 10^{-4}kg m^2$

So using again equation of conservation of the angular momentum:

$L=I_1 \omega_1 = I_2 \omega_2$

We find the new final angular speed:

$\omega_2 = \frac{I_1 \omega_1}{I_2}=\frac{(1.64\cdot 10^{-3})(35.0)}{5.57\cdot 10^{-4}}=103.0 rev/min$

7 0

2 years ago

Fossil fuels like gasoline or coal are examples of

disa [49]

Answer:

Nonrenewable Resources

8 0

2 years ago

What is the speed of an electromagnetic wave with a frequency of 100 mhz as it travels through a vacuum?

SCORPION-xisa [38]

Answer:

The speed of the wave with a frequency 100 mhz will be $3\times 10^{8}m/sec$

Explanation:

We have given that frequency of light is 100 mhz

We have to find the speed of light in vaccuum

We know that all electromagnetic waves travels in vaccum wth the same speed as the speed of light

And we know that speed of light is equal to $3\times 10^{8}m/sec$

So the speed of the wave with a frequency 100 mhz will be $3\times 10^{8}m/sec$

6 0

3 years ago

Listed following are three possible models for the long-term expansion (and possible contraction) of the universe in the absence

vazorg [7]

Answer:

do your best

Explanation:

<u>babyboiiii∛√</u>

8 0

2 years ago