1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
V125BC [204]
2 years ago
7

A reasonable estimate of the moment of inertia of an ice skater spinning with her arms at her sides can be made by modeling most

of her body as a uniform cylinder. Suppose the skater has a mass of 64 kg. One-eight of that mass is in her arms, which are 60 cm long and 20 cm from the vertical axis about which she rotates. The rest of her mass is approximately in the form of a 20-cm-radius cylinder. a. Estimate the skater's moment of inertia to two significant figures. b. If she were to hold her arms outward, rather than at her sides, would her moment of inertia increase, decrease, or remain unchanged? Explain.
Physics
1 answer:
alexgriva [62]2 years ago
8 0

Answer:

a) I = 1.44 Kg.m²

b) I = 3.12 Kg.m²

As rarm increases, her moment of inertia will increase.

Explanation:

Given

The skater's mass: M = 64 Kg

Mass of both arms: m = (M/8) = 64 Kg / 2 = 8 Kg

Mass of one arm: = marm = m/2 = 8 Kg / 2 = 4 Kg

Mass of her rest body: Mcyl = M - 2m = 64 Kg - 8 Kg = 56 Kg

rarm = 0.20 m

Rcyl = 0.20 m

Larm = 0.60 m

a) We apply the equation (Using the Steiner Theorem)

I = Icyl + Iarms

I = (Mcyl*Rcyl²/2) + 2*marm*rarm²

I = (56 Kg*(0.20 m)²/2) +2(4 Kg)(0.20 m)²

I = 1.44 Kg.m²

b) Suppose that the center of the mass of her outstretched arm is in the middle, so that the mass of the arm will be at a distance of 50 cm, then

rarm = 0.50 m

We apply the same equation, then

I = Icyl + Iarms

I = (Mcyl*Rcyl²/2) + 2*marm*rarm²

I = (56 Kg*(0.20 m)²/2) +2(4 Kg)(0.50 m)²

I = 3.12 Kg.m²

As rarm increases, her moment of inertia will increase.

You might be interested in
How many ways can you see that heat can transfer from the inside to the outside of your home on a cold day? List at least three
Yanka [14]

Answer: Heat transfers through brick walls and glass through conduction. In conduction heat is transferred by vibration of molecules. most energetic molecules vibrate and pass on the energy to less energetic molecules. Then they vibrate and further pass on the  energy. In this way heat is transferred out of the home. Heat also transfers through the leakage of warm air from doors and windows. This occurs through convection. In convection energy is transferred through bulk movement of liquid and air molecules. Heat also transfers from insulation. in insulation there is no material in between the layers. So heat transfer through insulation occurs through radiations that occurs by X-Rays, Ultravoilet rays etc.

4 0
3 years ago
A small car of mass m and a large car of mass 4m drive along a highway at constant speeds VS and VL. They approach a curve of ra
Arte-miy333 [17]

Answer:

v_S=\sqrt{2}v_L

Explanation:

The acceleration experimented while taking a curve is the centripetal acceleration a=\frac{v^2}{r}. Since a_S=2a_L, we have that: \frac{v_S^2}{r_S}=\frac{2v_L^2}{r_L}

They take the same curve, so we have: r_S=r_L=R

Which means: v_S^2=2v_L^2

And finally we obtain: v_S=\sqrt{2}v_L

4 0
3 years ago
How are kyanite crystals formed
aev [14]
It occurs as detrital grains in sedimentary rocks. It forms under extreme pressure.
3 0
3 years ago
A spring is 6.0cm long when it is not stretched, and 10cm long when a 7.0N force is applied. What force is needed to make it 20c
Artist 52 [7]

Answer:

Approximately 25\; {\rm N} (assuming that this spring is ideal.)

Explanation:

The displacement of a spring is the new length of the spring relative to the original length.

For example:

  • When the 6.0\; {\rm cm}-spring in this question is stretched to 10\; {\rm cm}, the displacement is x = (10\; {\rm cm} - 6.0\; {\rm cm}).
  • Likewise, if this spring is stretched to 20\; {\rm cm}, the displacement would be (20\; {\rm cm} - 6\; {\rm cm}).

If this spring is ideal, the force on the spring would be proportional to the displacement of the spring. In other words, if a force of F_{\text{a}} displaces this spring by x_{\text{a}}, while a force of F_{\text{b}} displaces this spring by x_{\text{b}}, then:

\displaystyle \frac{F_{\text{a}}}{x_{\text{a}}} = \frac{F_{\text{b}}}{x_{\text{b}}}.

In this question, it is given that a force of F_{\text{a}} = 7.0 \; {\rm N} would stretch this spring by x_{\text{a}} = (10\; {\rm cm} - 6.0\; {\rm cm}). Thus, the force F_{\text{b}} required to stretch this spring by x_{\text{a}} = (20\; {\rm cm} - 6.0\; {\rm cm}) would satisfy:

\displaystyle \frac{7.0\; {\rm N}}{10\; {\rm cm} - 6.0\; {\rm cm}}= \frac{F_{\text{b}}}{20\; {\rm cm} - 6.0\; {\rm cm}}.

Rearrange and solve for F_{\text{b}}:

\begin{aligned} F_{\text{b}} &= \frac{7.0\; {\rm N}}{10\; {\rm cm} - 6.0\; {\rm cm}} \, (20\; {\rm cm} - 6.0\; {\rm cm}) \\ &\approx 25\; {\rm N}\end{aligned}.

7 0
1 year ago
Help yet again :) A hockey player is skating on the ice at 15km/h. He shoots the puck at 138 km/h according to a radar gun on th
IceJOKER [234]

Answer:

speed of puck acc. to the radar gun = 138 km/h

speed of player = 15 km/h

since the player is in motion when he shoots, the speed of the puck will be the sum of the speed of the player and the speed at which he shot. so,

speed of puck = speed of player + speed of puck acc. to player

138 = 15 + speed of puck acc. to player

speed of puck acc. to player = 138 -15

speed of puck acc. to player = 123 km/h

Brainly this answer if you think it deserves it

7 0
3 years ago
Other questions:
  • Which of the following best describes alternating current? current that increases and decreases in temperature current that cons
    13·2 answers
  • Which best describes the definition for the atomic mass of an element
    9·2 answers
  • Vector L is 303 m long in a
    13·1 answer
  • When describing image formation in mirrors, what is the angle of incidence?
    6·2 answers
  • Describe the motionof an object that gas acceleration of 0 m/s
    9·1 answer
  • Solve for angles A-D
    11·1 answer
  • Two objects, X and Y, are held at rest on a horizontal frictionless surface and a spring is compressed between them. The mass of
    8·1 answer
  • From least to most dense, the media are: air, water, polyethylene, and flint glass.
    11·1 answer
  • A 0.250 kg car rest rolls down a frictionless incline from a starting height of 0.75 m what is the final velocity of the car? SH
    10·1 answer
  • PLEASE HELP ASAP I WILL GIVE YOU BRAINLEAST (15 POINTS)
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!