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e-lub [12.9K]
3 years ago
5

During a hard drive crash the read/write head scrapes against the disk with a coefficient of kinetic friction of µk and normal f

orce of N. Assume that just before the head crash the disk is rotating at ω0 rad/s, and the distance of the head from the disk axis is r. You can ignore any friction at the bearing (rotational axis of the disk). Assume that the disk is uniform, and has radius R and mass M. What is the angular acceleration associated with the torque from the crashed disk head?
Physics
1 answer:
Alex_Xolod [135]3 years ago
3 0

Answer:

 α = \frac{2 \mu \  N}{m \ r}

Explanation:

For this exercise we use Newton's equation for rotational motion

           ∑ τ = I α

the troque is

           α = Fr .r

the moment of inertia of a cylinder is

           I = ½ m r²

we substitute

         fr r = (½ m r²) α

the expression friction is

         fr = μ N

we substitute

         μ N r = ½ m r² α

       

         α = \frac{2 \mu \  N}{m \ r}

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I don’t have a question because I posted a photoz
Scorpion4ik [409]

Part a:

Q_{1} = 56

Q_{2} = 60

Q_{3} = 63

     The quartiles are found by finding the medium of the data, and then the mediums of the two different data sets on either side of the medium. The Q_{2} is the overall medium, Q_{1} is the medium of the first half, and Q_{3} is the medium of the second half.

-> How is the medium found? When finding the medium we put the values in order least to greatest and pick the middle value.

[] See attached

Part b:

The range is 7.

The interquartile range is the range of numbers between Q_{1} and Q_{3}. In other words, it is 50% of the data, directly in the middle.

This becomes 63 - 56 = 7

Part c:

79 is an outlier.

It is an outlier because it is 1.5 above or below (in this case, above) the interquartile range.

-> 63 + (7 + \frac{7}{2}) ≤ 79

-> 63 + 10.5 ≤ 79

-> 73.5 ≤ 79

Have a nice day!

     I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly.

- Heather

7 0
2 years ago
If a transformer has a primary with 100 V and fifty coils, and a secondary that yields 20 V, how many coils are on the secondary
melomori [17]
Ideally, if all the magnetic of one winding cuts the other winding, and there isn't any loss in the transformer core or the resistance of the wire, then the voltage across each winding is proportional to the number of turns in its coil.

If you apply 100 V to a winding of 50 turns, then a winding that yields 20 volts
must be wound with

(20/100) of 50 turns = 10 turns
7 0
3 years ago
A planetâs moon revolves around the planet with a period of 39 Earth days in an approximately circular orbit of radius of 4.8Ã10
Alchen [17]

Answer:

v = 895 m/s

Explanation:

Time period is given as 39 Earth Days

T = 39 days \times 24 hr \times 3600 s

T = 3369600 s

now the radius of the orbit is given as

r = 4.8 \times 10^8 m

so the total path length is given as

L = 2 \pi r

L = 2\pi (4.8 \times 10^8)

L = 3.015 \times 10^9

now the speed will be given as

v = \frac{L}{T}

v = \frac{3.015 \times 10^9}{3369600}

v = 895 m/s

7 0
3 years ago
Describe the ratio of kinetic energy and potential energy the skateboarder will have at each of the following points in her ride
amm1812

Answer:

no answer

Explanation:

7 0
2 years ago
If two materials are made from different kinds of atoms, what else should you expect to be different?
Volgvan
<span>B. The properties they have</span>
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