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3 years ago

12

It takes 15 minutes to walk to the mall from your house at an average velocity of 1.1 m/s to the east. What is the displacement

from your house to the mall?

1 answer:

Anna11 [10]3 years ago

4 0

15 minutes = 15*60 = 900 seconds

900x1.1 = 990 m

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Starting from rest, a disk rotates about its central axis with constant angular acceleration. in 6.00 s, it rotates 44.5 rad. du

Klio2033 [76]

a. The disk starts at rest, so its angular displacement at time $t$ is

$\theta=\dfrac\alpha2t^2$

It rotates 44.5 rad in this time, so we have

$44.5\,\mathrm{rad}=\dfrac\alpha2(6.00\,\mathrm s)^2\implies\alpha=2.47\dfrac{\rm rad}{\mathrm s^2}$

b. Since acceleration is constant, the average angular velocity is

$\omega_{\rm avg}=\dfrac{\omega_f+\omega_i}2=\dfrac{\omega_f}2$

where $\omega_f$ is the angular velocity achieved after 6.00 s. The velocity of the disk at time $t$ is

$\omega=\alpha t$

so we have

$\omega_f=\left(2.47\dfrac{\rm rad}{\mathrm s^2}\right)(6.00\,\mathrm s)=14.8\dfrac{\rm rad}{\rm s}$

making the average velocity

$\omega_{\rm avg}=\dfrac{14.8\frac{\rm rad}{\rm s}}2=7.42\dfrac{\rm rad}{\rm s}$

Another way to find the average velocity is to compute it directly via

$\omega_{\rm avg}=\dfrac{\Delta\theta}{\Delta t}=\dfrac{44.5\,\rm rad}{6.00\,\rm s}=7.42\dfrac{\rm rad}{\rm s}$

c. We already found this using the first method in part (b),

$\omega=14.8\dfrac{\rm rad}{\rm s}$

d. We already know

$\theta=\dfrac\alpha2t^2$

so this is just a matter of plugging in $t=12.0\,\mathrm s$ . We get

$\theta=179\,\mathrm{rad}$

Or to make things slightly more interesting, we could have taken the end of the first 6.00 s interval to be the start of the next 6.00 s interval, so that

$\theta=44.5\,\mathrm{rad}+\left(14.8\dfrac{\rm rad}{\rm s}\right)t+\dfrac\alpha2t^2$

Then for $t=6.00\,\rm s$ we would get the same $\theta=179\,\rm rad$ .

7 0

4 years ago

A climber using bottled oxygen accidentally drops the oxygen bottle from an altitude of 4500 m. If the bottle fell straight down

Trava [24]

Answer:

v= 300 m/s

Explanation:

Given that

altitude ,h= 4500 m

The mass ,m = 3 kg

Lets take acceleration due to gravity , g= 10 m/s²

The speed before impact at sea level = v

Initial speed ,u = 0 m/s

We know that

v²=u²+2 g h

v=final speed

u=initial speed

h=height

Now by putting the values in the above equation

v² = 0²+ 2 x 10 x 4500

v²=90000

v= 300 m/s

Therefore the speed at sea level will be 300 m/s.

3 0

3 years ago

A ball is launched up a semicircular chute in such a way that at the top of the chute, just before it goes into free fall, the b

Mariulka [41]

We have centripetal acceleration = $v^2/r = 2g$

So, v = $\sqrt{2gr}$

Now by equation of motion we have S= ut +0.5a $t^2$

S =displacement, u = initial velocity, a= acceleration and t = time

Here S = 2r and a = g , u = 0

$2r = 0+\frac{1}{2} *g*t^2$

$t = \sqrt{\frac{4r}{g} }$

Distance traveled in horizontal direction = $\sqrt{2gr}*\sqrt{\frac{4r}{g} }= \sqrt{8r^2} =2r\sqrt{2}$

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4 years ago

The state in which a star's gravitational collapse is balanced between gravity pushing inward and gas pressure pushing outward i

Andrew [12]

The relation between temperature and pressure is called the "equation of state of the gas". or "Hydrostatic equilibrium in ordinary star". Take for example a balloon, it will have a larger spherical shape, if the pressure inside exerted by the gas on a wall of a balloon balance the inward force exerted by the outside atmospheric pressure. In a dying star which is being compressed by gravity, the gas is being squeezed so the molecules is moving rapidly, resulting to a very high temperature, and this provide a balance that counteract or balances the compressive force of gravity. The very high temperature inside the star is needed to balance the force of gravity, and it is provide by "nuclear fusion energy" or else the star would collapse under the force of gravity. Depending on the size or mass of the star, it will either become, a "neutron star" or a "black hole".

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3 years ago

Read 2 more answers

Which is NOT considered as a property of electromagnetic waves: 5

OlgaM077 [116]

Answer:

require a medium to propagate

Explanation:

this is because electromagnetic waves can travel through vacuum at the speed of 3.0 x 10^8 m/s

because they don't need particles to transfer energy

hope this helps

4 0

3 years ago