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blondinia [14]
3 years ago
8

Disk A, with a mass of 2.0 kg and a radius of 60 cm , rotates clockwise about a frictionless vertical axle at 20 rev/s . Disk B,

also 2.0 kg but with a radius of 40 cm , rotates counterclockwise about that same axle, but at a greater height than disk A, at 20 rev/s . Disk B slides down the axle until it lands on top of disk A, after which they rotate together.After the collision, what is their common angular speed (in rev/s) and in which direction do they rotate?
Physics
1 answer:
Vladimir79 [104]3 years ago
6 0

Answer:

Explanation:

  • let m1 = 2 kg
  • r1 = 60 cm = 0.6 m
  • w1 = -20 rev/s (clockwise)

I1 = 0.5 x m1 x r1²

= 0.5 x 2 x 0.6²

= 0.36 kg.m²

m2 = 2 kg

r2 = 40 cm = 0.4 m

w2 = 20 rev/s (counter clockwise)

I2 = 0.5 x m2 x r2²

= 0.5 x 2 x 0.4²

= 0.16 kg.m²

let wf be the final angular velocity of the two disks.

Applying conservation of angular momentum ;

(I1 + I2) x wf = I1 x w1 + I2 x w2

wf = (I1 x w1 + I2 x w2) / (I1 + I2)

= (0.36 x (-20) + 0.16 x 20 )/(0.36 + 0.16)

= -7.69rev/s

The negative sign indicates the disks rotate clockwise direction.

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Answer:

B) \frac{2}{3}

Explanation:

The electric force between charges can be determined by;

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Where: F is the force, k is the Coulomb's constant, q_{1} is the value of the first charge, q_{2} is the value of the second charge, r is the distance between the centers of the charges.

Let the original charge be represented by q, so that;

q_{1} = 2q

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F = q_{1}q_{2} x \frac{k}{r^{2} }

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F = \frac{2}{3} x \frac{kq}{r^{2} }

The electric force between the given charges would change by \frac{2}{3}.

4 0
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Use the drop-down menus to complete each sentence about the layers of the atmosphere. If the did not exist, Earth might be destr
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Answer:

If the mesosphere did not exist, Earth might be destroyed by chunks of rock from space.

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Both the trophosphere and mesosphere get colder as altitude increases.

The ozone in the stratosphere protects people from ultraviolet (UV) radiation.

The thermosphere has the highest temperature of any layer in Earth's atmosphere.

Explanation:

Different layers of the atmosphere are;

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It is the lowest layer of atmosphere that begins at ground level and extends upward to about 10 km. In this layer, all organisms live, weather occurs and most clouds appear. As altitude increases, the temperature decreases i.e., the layer gets colder.

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This layer is located at the top of the troposphere  and extends up to about 50 km from Earth's surface. The ozone layer present in this layer absorbs high-energy ultraviolet (UV) light from the Sun. Here, the temperature rises with altitude. The passenger jets are usually fly in this layer.

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