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3 years ago

Three balls with the same radius 21 cm are in water. Ball 1 floats, with

Physics

1 answer:

Masteriza [31]3 years ago

7 0

Answer:

Explanation:

A )

The ball floats with half of it exposed above the water level . So it must have density half that of water . In other words its density must have been 500 kg / m³

B )

Tension in the ball will be equal to net force acting on the ball

Net force on the ball = buoyant force - weight .

4/3 x π x .21³ x 10⁻⁶ x 9.8 ( 1000 - 893 )

= 40.65 x 10⁻⁶ N .

C )Tension in the 3 rd ball will be equal to net force acting on the ball

Net force on the ball = weight - buoyant force

= 4/3 x π x .21³ x 10⁻⁶ x 9.8 ( 1320 - 1000 )

= 121.6 x 10⁻⁶ N .

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Gre4nikov [31]

Here since both children and merry go round is our system and there is no torque acting on this system

So we will use angular momentum conservation in this

$I_1\omega_1 = I_2\omega_2$

now here we have

$I_1 = \frac{MR^2}{2} + m_1R^2 + m_2R^2$

$I_1 = \frac{100(1.60)^2}{2} + (22 + 28)(1.60)^2$

$I_1 = 256$

Now when children come to the position of half radius

then we will have

$I_2 = \frac{MR^2}{2} + m_1(\frac{R}{2})^2 + m_2(\frac{R}{2})^2$

$I_2 = \frac{100(1.6)^2}{2} + (28 + 22)(0.8)^2$

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now from above equation we have

$256 (20.0 rpm) = 160(\omega_2)$

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3 years ago

A rocket burns fuel at a rate of 249 kg/s and exhausts the gas at a relative speed of 2 km/s. Find the thrust of the rocket. Ans

tino4ka555 [31]

1.791MN is the answer

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3 years ago

What is the power generated by a 45 kg person who walks up a flight of 12 stairs, each 30 cm high, in 12 s?

Free_Kalibri [48]

The total distance covered by the person is 12 times the height of each stair:
$\Delta h=12 \cdot 30 cm=360 cm=3.60 m$

The work done by the person to climb the stairs is equal to the increase in his gravitational potential energy:
$W= \Delta U=mg \Delta h=(45 kg)(9.81 m/s^2)(3.60 m)=1589.2 J$

And therefore, the power generated by the person in 12 s is the work done divided by the time taken:
$P= \frac{W}{t}= \frac{1589.2 J}{12 s}=132.3 W$

So, the correct answer is B.

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4 years ago

A battery is the power source for what type of current

patriot [66]

Answer: DC Current

Explanation:

Battery is a source of constant potential difference and it will create a constant voltage across any conductor

due to this constant voltage difference the current in this conductor will remain constant

So here since the voltage across the conductor is constant so we can say that current in the conductor will remain constant and hence this is known as DC current.

While for variable current in direction and magnitude is to be obtained only when the conductor is connected with AC voltage source as we know that AC voltage is variable with magnitude and direction both

A battery is the power source for DC type of current. A battery is a source of constant potential difference that produces a constant current unlike in AC source where the voltage and hence the current changes its polarity continuously.Hence, the current produced by battery is direct current and not Alternating current.

Hope this helps........ Stay safe and have a Merry Christmas!!!!!! :D

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BaLLatris [955]

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4 years ago