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Law Incorporation [45]
2 years ago
7

A disk of mass m and radius r is initially held at rest just above a larger disk of mass M and radius R that is rotating at angu

lar speed ωi. What is the final angular speed of the disks after the top one is dropped onto the bottom one and they stop slipping on each other? Note: the moment of inertia of a disk of mass M and radius R about an axis through its center and perpendicular to the disk is I = (1/2)MR .
Physics
1 answer:
Leto [7]2 years ago
6 0

Answer:

Explanation:

Moment of inertia of larger disk   I₁ = 1/2 MR²

Moment of inertia of smaller  disk   I₂ = 1/2 m r ²

Initial angular velocity

We shall apply law of conservation of angular momentum .

initial total momentum = final angular momentum

I₁ X ωi  = ( I₁ + I₂ )ωf

1/2 MR² x ωi = 1/2 ( m r² + MR² ) ωf

ωf =  ωi   / ( 1 + m r²/MR² )

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The gravity tractor is a proposed spacecraft that will fly close to an asteroid whose trajectory threatens to impact the Earth.
Talja [164]

Answer:

F_g=461lb_f

Explanation:

First calculate the mass of the asteroid. To do so, you need to find the volume and know the density of iron.

If r = d/2 = 645ft, then:

V = \frac{4}{3} \pi r^3

V = 1.124*10^{9}ft^3

So

\delta_{iron}=m/V=491lb/ft^3

m=V*\delta=5.519*10^{11}lb

Once you  know both masses, you can calculate the force using Newton's universal law of gravitation:

F_g=G\frac{m_1m_2}{d^2}

Where G is the gravitational constant:

G= 1.068846 * 10^{-9} ft^3 lb^{-1} s^{-2}

F_g=461lb_f

4 0
2 years ago
Consider a basketball player spinning a ball on the tip of a finger. If a player performs 1.91 J1.91 J of work to set the ball s
Black_prince [1.1K]

Answer:

ω = 4.07 rad/s

Explanation:

By conservation of the energy:

W = ΔK

1.91J = I/2*\omega^2

where I = 2/3*m*R^2=0.23kg.m^2

Solving for ω:

\omega = \sqrt{W*2/I} =4.07rad/s

7 0
2 years ago
a crane lifts a 35000 N steel girder a distance of 25 m in 45 s. How much power did the crane require to lift the girder
Angelina_Jolie [31]
Hello.

The formula for Power is Work divided by Time; however, we do not have our value for Work - yet.
To find for the Work inputted, we need to use its formula: Force * Distance.

Let's multiply our Force by our Distance. Remember that our Force is always  measured in Newtons (N), and our Distance is measured by Meters (M).
35,000 * 25 = 875,000 J (Unit for Work is "J" or "Joules")

Now that we have the value for Work, let's apply it to our Power formula.
P = 875,000 / 45; 19,444.44~

The Power required to lift the girder is 1944.44~ W (Unit for Power is "W" or "Watts").

I hope this helps!
7 0
2 years ago
Air at 27 ºC and 5 atm is throttled by a valve to 1 atm. If the valve is adiabatic and the change in kinetic energy is negligibl
Citrus2011 [14]

Answer:

27 °C

Explanation:

BY the statement of the question it is clear that it is about an ideal gas - and hence if change in KE is about zero - then there will be no change of temperature.

So, answer is 27 °C

4 0
2 years ago
Two of the types of ultraviolet light, uva and uvb, are both components of sunlight. their wavelengths range from 320 to 400 nm
a_sh-v [17]

In light energy, the higher the frequency, the greater the energy a light contain.

We know for a certain that frequency is just the reciprocal of wavelength:

frequency = 1 / wavelength

Calculating for frequencies:

f UVA = 1/320 to 1/400

f UVA = 0.0031 to 0.0025

 

f UVB = 1/290 to 1/320

f UVB = 0.0034 to 0.0031

Since UVB has higher frequency range, then it has higher energy than UVA.

7 0
2 years ago
Read 2 more answers
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