Which statement is true?

What is the main source of energy

jolli1 [7]

Sun is the main source of energy

8 0

3 years ago

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The loudness of sound is the wave's ____.

Anni [7]

194db is the loudest Sound wave

5 0

3 years ago

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A circular disc of mass 20kg and radius 15cm is mounted in an horizontal cylindrical axle of radius

disa [49]

Using the concepts of energy, rotational Newton's second law and rotational kinematics we can find the kinematic energy of the system formed by the disk and the cylindrical axis

KE = 0.23 J

given parameters

Disk radius R = 15 cm = 0.15 m
Cylinder radius r = 1.5 cm = 0.0015 m
Disk mass M = 20 kg
Time t = 1.2 s
Force F = 12 N

to find

Kinetic energy (KE)

This exercise must be solved in parts:

1st part. Endowment kinetic energy is the energy due to the circular motion of an object and is described by the equation

KE = ½ I w²

Where KE is the kinetic energy, I the moment of inertia and w the angular velocity

The moment of inertia is a magnitude that measures the inertia for rotational movement, it is a scalar quantity, therefore it is additive. In this system it is composed of two bodies, the disk and the cylindrical axis, for which the total moment of inertia it is

I_{ total} = I_{ disk} + I_{ cylinder}

the moments of inertia with respect to an axis passing through the center of mass are tabulated

disk I_{disk} = ½ M R²

cylinder I_{cylinder} = ½ m r²

where M and m are the masses of the disk and cylinder respectively, R and r their radii

I_{total} = ½ (M R² + m r²) = ½ M R² ( $1 + \frac{m}{M} \ (\frac{r}{R})^2$ )

I_{total} = ½ M R² ( $1+ \frac{m}{20} (\frac{0.015}{0.15} )^2$ ) = $\frac{1}{2}$ M R² (1 + 0.005 m)

As the shaft mass is much lighter than the disk mass , the last term is very small, which is why we despise it.

I_{total} = ½ M R²

2nd part. Let's use Newton's second law for endowment motion

τ = I α

α = $\frac{\tau }{I_{total}}$ l

τ = F R

α = $\frac{F \ R}{I_{total}}$

With the rotational kinematics expressions, we assume that the system starts from rest (w₀ = 0)

w = w₀ + α t

where w is the angular velocity, alpha is the angular acceleration and t is the time

w = 0 + $\frac{\tau }{I_{total}} \ t$

we substitute in the kinetic energy equation

KE = ½ I_{total} ( $\frac{ \tau }{I_{total}} \ t$ )²

KE = ½ $\frac{ \tau^2 }{I_{total}} \ t^2$

let's substitute

KE = $\frac{F^2 \ R^4}{M \ R^2 } \ t^2$

KE = F² R² t² / M

let's calculate

KE = 12² 0.15² 1.2² / 20

KE = 0.23 J

With the concepts of energy and rotational kinematics we can find the kinetic energy of the system is

KE = 0.23 j

learn more about rotational kinetic energy here:

brainly.com/question/20261989

4 0

2 years ago

Does air resistence decrease with speed

dybincka [34]

Answer:

yes

Explanation:

because when you slow down, the resistance slows with the speed.

3 0

3 years ago

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Consider two diffraction gratings with the same slit separation. The only difference between the two gratings is that one gratin

kobusy [5.1K]

Answer:

True The grid with more slits gives more angle separation increases

True. The grating with 10 slits produces better-defined (narrower) peaks

Explanation:

Such a system can be seen as a diffraction network in this case with different number of lines per unit length, the expression for the constructive interference of a diffraction network is

d sin θ = m λ

where d is the distance between slits or lines, m the order of diffraction and λ the wavelength.

For network with 5 slits

d = 1/5 = 0.2

For the network with 10 slits

d = 1/10 = 0.1

let's calculate the separation (teat) for each one

θ = sin⁻¹ (m λ / d)

for 5 slits

θ₅ = sin⁻¹ (m λ 5)

for 10 slits

θ₁₀ = sin⁻¹ (m λ 10)

we can appreciate that for more slits the angle increases

the intensity of a series of slits is

I = I₀ sin²2 (N d/2) / sin² d/2)

when there are more slits (N) the peaks have greater intensity and are more acute (half width decreases)

let's analyze the claims

False

True The grid with more slits gives more angle separation increases

False

True The expression for the intensity of the diffraction peaks the intensity of the peaks increases with the number of slits as well as their spectral width decreases

False

5 0

3 years ago