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max2010maxim [7]

3 years ago

7

An ice skater spins at 2.5 rev/s when his arms are extended. He draws his arms in and spins at 10.0 rev/s. By what factor does h

is moment of inertia change in the process?

1 answer:

Rainbow [258]3 years ago

4 0

Answer:

The moment of inertia decreased by a factor of 4

Explanation:

Given;

initial angular velocity of the ice skater, ω₁ = 2.5 rev/s

final angular velocity of the ice skater, ω₂ = 10.0 rev/s

During this process we assume that angular momentum is conserved;

I₁ω₁ = I₂ω₂

Where;

I₁ is the initial moment of inertia

I₂ is the final moment of inertia

$I_2 = \frac{I_1 \omega_1}{\omega_2} = \frac{I_1*2.5}{10} \\\\I_2 = 0.25I_1 = \frac{1}{4}I_1$

Therefore, the moment of inertia decreased by a factor of 4

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On a Saturday afternoon, you decide to pay a neighborhood kid to mow your lawn. The kid usesa manual push lawn mower with a mass

Mars2501 [29]

Answer with Explanation:

We are given that

A.Mass,m=12 kg

$\theta=53^{\circ}$

$\mu_k=0.16$

Speed,v=1.5m/s

Net force in x direction must be zero

$F_{net}=0$

$Fsin\theta-f=0$

$Fsin\theta=f$

Net force in y direction

$N-mg-Fcos\theta=0$

$N=mg+Fcos\theta$

$f=\mu_kN=\mu_k(mg+Fcos\theta)$

$Fsin\theta=\mu_k(mg+Fcos\theta)$

$Fsin\theta=\mu_kmg+\mu_kFcos\theta$

$Fsin\theta-\mu_kFcos\theta=\mu_kmg$

$F(sin\theta-\mu_kcos\theta)=\mu_kmg$

$F=\frac{\mu_kmg}{sin\theta-\mu_kcos\theta}$

Power,P=Fv

$P=\frac{\mu_kmg}{sin\theta-\mu_kcos\theta}v$

Where $g=9.8m/s^2$

B.Substitute the values

$P=\frac{0.16\times 12\times 9.8}{sin53-0.16cos53}\times 1.5$

$P=40.17W$

6 0

4 years ago

Kyle has a mass of 54kg and is moving at 3 m/s what is his kinetic energy

Mars2501 [29]

Answer:

243J

Explanation:

K.E = 1/2 x 54 x 3^2

K.E = 1/2 x 54 x 9

K.E = 1/2 x 486

K.E = 486/2

K.E = 243J

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4 years ago

Rose has been working as a receptionist for 20 years. One day, she receives a check in the mail for $750,000—an inheritance from

sergey [27]

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3 years ago

Read 2 more answers

Density: Two blocks, A and B, are put in a tank of water. Block A has a density of 1.21 g/cm³. Block B has a density of 1.37 g/c

stira [4]

Answer:

Block A

Explanation:

Block A will float higher in the water compared to the second Block.

The density of water is 1g/cm³.

According to the principle of floatation "an object that floats in a liquid will displace equal amount of fluid to the weight of the object".

A body will become more submerged in water if it has more density because density is the mass per volume of body.

An object with a higher density than another will sink in the liquid of the one with lesser density.

Object A has lesser density and will float higher up and displace very little water.
Object B has higher density and will be more submerged.

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3 years ago

2. Below what depth would a submarine have to submerge so that it would not be swayed by surface waves with a wavelength of 24 m

Travka [436]

<u>Answer:</u> Below 12m of depth, the submarine has to submerge so that it would not be swayed by surface waves

<u>Explanation:</u>

To avoid the surface waves, a submarine has to submerge below the wave base. It is the position below which the motion of the waves is negligible.

This wave base is equal to half of the wavelength. The equation becomes:

Wave base = $\frac{\text{Wavelength}}{2}$

We are given:

Wavelength = 24 m

Putting values in above equation, we get:

Wave base = $\frac{24m}{2}=12m$

Hence, below 12m of depth, the submarine has to submerge so that it would not be swayed by surface waves

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3 years ago