Một loa phát ra với cường độ âm là 40 (W/m2<br><br> ). Mức cường độ âm của loa thuộc phạm vi?

A bug flies at a velocity of 0.75 m/s into an oncoming breeze blowing at 0.25 m/s. What is the resultant velocity of the bug?

MakcuM [25]

0.5m/s. Take the velocity of the bug and subtract from the velocity of the oncoming breeze because they are opposite. If the breeze was in the same direction that the bug was flying, then your answer would be the sum of the two.

4 0

3 years ago

The motivation for Isaac Newton to discover his laws of motion was to explain the properties of planetary orbits that were obser

Mandarinka [93]

Answer:

Explanation:

We know that , for an object to remain in circular motion , a force towards centre is required which is called centripetal force. In the circular motion of

satellites around planet , this force is provided by the gravitational attraction between satellite and planet.

If M be the mass of planet and m be the mass of satellite, G be gravitational constant and R be the distance between planet and satellite or R be the radius of orbit

Gravitational force = G Mm / R²

If v be the velocity with which satellite is orbiting

centripetal force

= m v² /R

Centripetal force = gravitational attraction

m v² /R = G Mm / R²

v = $\sqrt{\frac{GM}{R} }$

Time period = time the satellite takes to make one rotation

= distance / orbital velocity

= 2πR/ v

= $\frac{2\pi R\sqrt{R} }{\sqrt{GM} }$

T = $\frac{2\pi R^\frac{3}{2} }{\sqrt{GM} }$

3 0

3 years ago

The spherical side mirror on a car is convex and has a radius of curvature of 25 cm. Another car is following, 20 m behind the m

svlad2 [7]

Answer:

(D) 0.99 cm

Explanation:

Given that the radius of curvature of the mirror is 25 cm.

And another car is following which is behind the mirror of 20 m.

$u=20m=2000cm$

Focal length is half of the radius of curvature and it is negative for convex lens.

Now the mirror formula.

$1/v+1/u=1/f$

So,

$1/v+1/2000=-1/(25/2)\\1/v=-1/2000-1/12.5\\v=-12.422cm$

Now

Magnification is,

$m=-v/u$

So,

$m=12.422/2000=0.00621$

So, Height of the image

$mh=0.00621\times 1.6 m\\mh=0.0099m\\mh=0.99cm$

Therefore, the image height is 0.99 cm.

4 0

3 years ago

Consider a uniform solid sphere of radius R and mass M rolling without slipping. Which form of its kinetic energy is larger, tra

castortr0y [4]

Answer:

A. Its translational kinetic energy is larger than its rotational kinetic energy.

Explanation:

Given that

Radius = R

Mass = M

We know that mass moment of inertia for the solid sphere

$I=\dfrac{2}{5}MR^2$

Lets take angular speed =ω

Linear speed =V

Condition for pure rolling , V= ω R

Rotation energy ,RE

$RE=\dfrac{1}{2}I\omega^2$

$RE=\dfrac{1}{2}\times \dfrac{2}{5}MR^2\times \omega^2$

$RE=\dfrac{1}{5}\times MR^2\times \omega^2$

$RE=\dfrac{1}{5}\times MV^2$

RE= 0.2 MV²

The transnational kinetic energy TE

$TE=\dfrac{1}{2}MV^2$

TE= 0.5 MV²

From above we can say that transnational energy is more than rotational energy.

Therefore the answer is A.

3 0

2 years ago

MANY POINTS!!! PLZ! I NEED HELP!!!

liq [111]

Cetane rating of the diesel ensures the low temperature and uniform combustion. Centane number is just opposite to the octane number of petrol engine, cetane number of diesel determines at which temperature the diesel will going to autoignite.

8 0

3 years ago

Một loa phát ra với cường độ âm là 40 (W/m2 ). Mức cường độ âm của loa thuộc phạm vi?