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Natasha2012 [34]

3 years ago

10

Think about holding a glass of cold water. Your hand is warmer than the glass. Do the particles in your hand or those in the gla

ss of cold water move faster? Why?

1 answer:

choli [55]3 years ago

6 0

technically usually the warmer object/substances particles move master which causes friction among the particles plus the kinetic energy being converted to thermal energy, so i would say the hand.

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Initially, a 2.00-kg mass is whirling at the end of a string (in a circular path of radius 0.750 m) on a horizontal frictionless

drek231 [11]

Answer:

$v_f = 15 \frac{m}{s}$

Explanation:

We can solve this problem using conservation of angular momentum.

The angular momentum $\vec{L}$ is

$\vec{L} = \vec{r} \times \vec{p}$

where $\vec{r}$ is the position and $\vec{p}$ the linear momentum.

We also know that the torque is

$\vec{\tau} = \frac{d\vec{L}}{dt} = \frac{d}{dt} ( \vec{r} \times \vec{p} )$

$\vec{\tau} = \frac{d}{dt} \vec{r} \times \vec{p} + \vec{r} \times \frac{d}{dt} \vec{p}$

$\vec{\tau} = \vec{v} \times \vec{p} + \vec{r} \times \vec{F}$

but, as the linear momentum is $\vec{p} = m \vec{v}$ this means that is parallel to the velocity, and the first term must equal zero

$\vec{v} \times \vec{p}=0$

so

$\vec{\tau} = \vec{r} \times \vec{F}$

But, as the only horizontal force is the tension of the string, the force must be parallel to the vector position measured from the vertical rod, so

$\vec{\tau}_{rod} = 0$

this means, for the angular momentum measure from the rod:

$\frac{d\vec{L}_{rod}}{dt} = 0$

that means :

$\vec{L}_{rod} = constant$

So, the magnitude of initial angular momentum is :

$| \vec{L}_{rod_i} | = |\vec{r}_i||\vec{p}_i| cos(\theta)$

but the angle is 90°, so:

$| \vec{L}_{rod_i} | = |\vec{r}_i||\vec{p}_i|$

$| \vec{L}_{rod_i} | = r_i * m * v_i$

We know that the distance to the rod is 0.750 m, the mass 2.00 kg and the speed 5 m/s, so:

$| \vec{L}_{rod_i} | = 0.750 \ m \ 2.00 \ kg \ 5 \ \frac{m}{s}$

$| \vec{L}_{rod_i} | = 7.5 \frac{kg m^2}{s}$

For our final angular momentum we have:

$| \vec{L}_{rod_f} | = r_f * m * v_f$

and the radius is 0.250 m and the mass is 2.00 kg

$| \vec{L}_{rod_f} | = 0.250 m * 2.00 kg * v_f$

but, as the angular momentum is constant, this must be equal to the initial angular momentum

$7.5 \frac{kg m^2}{s} = 0.250 m * 2.00 kg * v_f$

$v_f = \frac{7.5 \frac{kg m^2}{s}}{ 0.250 m * 2.00 kg}$

$v_f = 15 \frac{m}{s}$

8 0

3 years ago

Is a cow a producer? Or a consumer or decomposer?

klemol [59]

Is a cow a producer? Or a consumer or decomposer? Cow is a consumer

7 0

2 years ago

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2. For each pair of variables, identify which is the independent and which is the dependent variable. a. How much gas is left in

Korvikt [17]

For each pair Independent variable and the dependent variable is -

a. How much gas is left in the gas tank vs. how far the car has traveled.

Independent variable = how far the car has traveled

dependent variable = How much gas is left in the gas tank

b. How much money you've spent vs. how much money is in your wallet.

Independent variable = How much money you've spent

dependent variable = how much money is in your wallet.

c. How far a toy car traveled vs. how much time went by

Independent variable = how much time went by

dependent variable = How far a toy car traveled

An independent variable in any experiment or research is a variable that is manipulated or changed in the experiment, this change leads to a direct effect on the dependent variable.

A dependent variable is a variable that is directly affected by the independent variable and it is the variable that is measured or tested in an experiment.

Thus,

a. How much gas is left in the gas tank vs. how far the car has traveled.

Independent variable = how far the car has traveled

dependent variable = How much gas is left in the gas tank

b. How much money you've spent vs. how much money is in your wallet.

Independent variable = How much money you've spent

dependent variable = how much money is in your wallet.

c. How far a toy car traveled vs. how much time went by

Independent variable = how much time went by

dependent variable = How far a toy car traveled

Learn more about dependent variables:

brainly.com/question/1670595:

3 0

2 years ago

Why is traveling between the stars (by creatures like us) difficult?

mariarad [96]

Answer:

Stars are at large distances that even light takes thousands of years to reach us from there.

for example, alpha centauri is 4300 light years away from earth and it is considered the nearest star to us, this means that light from there takes 4300 years to reach us and with a spaceships that can move with the speed of light is would take us 4300 years to get there which is imposible to live for that long.

hence, it is difficult to move between the stars.

4 0

3 years ago

Average velocity is different than average speed because calculating average velocity involves ?

Studentka2010 [4]

Direction!

Velocity is a vector quantity and speed is a scalar quantity. Vector quantities includes both magnitude and direction, while scalar quantities only have magnitude. :)

5 0

3 years ago

Read 2 more answers