Answer:
![64 cm^3](https://tex.z-dn.net/?f=64%20cm%5E3)
Explanation:
<u>Density
</u>
The density of a substance is the mass per unit volume. The density varies with temperature and pressure.
The formula to calculate the density of a substance of mass (m) and volume (V) is:
![\displaystyle \rho=\frac{m}{V}](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Crho%3D%5Cfrac%7Bm%7D%7BV%7D)
We have a cube-shaped piece of copper of 4 cm of side length. The volume of the piece is:
![V=(4\ cm)^3=64\ cm^3](https://tex.z-dn.net/?f=V%3D%284%5C%20cm%29%5E3%3D64%5C%20cm%5E3)
Surprisingly, no other magnitude is required, thus the answer is:
![\mathbf{64 cm^3}](https://tex.z-dn.net/?f=%5Cmathbf%7B64%20cm%5E3%7D)
Explanation:
d = Diameter of wheel = 27 cm
r = Radius = ![\frac{d}{2}=\frac{27}{2}=13.5\ cm](https://tex.z-dn.net/?f=%5Cfrac%7Bd%7D%7B2%7D%3D%5Cfrac%7B27%7D%7B2%7D%3D13.5%5C%20cm)
m = Mass of wheel = 800 g
= Initial angular velocity = ![245\times \frac{2\pi}{60}\ rad/s](https://tex.z-dn.net/?f=245%5Ctimes%20%5Cfrac%7B2%5Cpi%7D%7B60%7D%5C%20rad%2Fs)
Equation of rotational motion
![\omega_f=\omega_i+\alpha t\\\Rightarrow \alpha=\frac{\omega_f-\omega_i}{t}\\\Rightarrow \alpha=\frac{0-245\times \frac{2\pi}{60}}{50}\\\Rightarrow \alpha=-0.51312\ rad/s^2](https://tex.z-dn.net/?f=%5Comega_f%3D%5Comega_i%2B%5Calpha%20t%5C%5C%5CRightarrow%20%5Calpha%3D%5Cfrac%7B%5Comega_f-%5Comega_i%7D%7Bt%7D%5C%5C%5CRightarrow%20%5Calpha%3D%5Cfrac%7B0-245%5Ctimes%20%5Cfrac%7B2%5Cpi%7D%7B60%7D%7D%7B50%7D%5C%5C%5CRightarrow%20%5Calpha%3D-0.51312%5C%20rad%2Fs%5E2)
Moment of inertia is given by
![M=\frac{1}{2}mr^2\\\Rightarrow M=\frac{1}{2}\times 0.8\times 0.135^2\\\Rightarrow M=0.00729\ kgm^2](https://tex.z-dn.net/?f=M%3D%5Cfrac%7B1%7D%7B2%7Dmr%5E2%5C%5C%5CRightarrow%20M%3D%5Cfrac%7B1%7D%7B2%7D%5Ctimes%200.8%5Ctimes%200.135%5E2%5C%5C%5CRightarrow%20M%3D0.00729%5C%20kgm%5E2)
Torque is given by
![\tau=I\alpha\\\Rightarrow \tau=0.00729\times -0.51312\\\Rightarrow \tau=-0.0037406448\ Nm](https://tex.z-dn.net/?f=%5Ctau%3DI%5Calpha%5C%5C%5CRightarrow%20%5Ctau%3D0.00729%5Ctimes%20-0.51312%5C%5C%5CRightarrow%20%5Ctau%3D-0.0037406448%5C%20Nm)
The torque the friction exerts is -0.0037406448 Nm
For more information on torque and moment of inertia refer
brainly.com/question/13936874
brainly.com/question/3406242
When two tectonic plates move in opposite directions, it causes magma to rise, creating a new seafloor.
Answer:
The wavelength of the visible line in the hydrogen spectrum is 434 nm.
Explanation:
It is given that, the wavelength of the visible line in the hydrogen spectrum that corresponds to n₂ = 5 in the Balmer equation.
For Balmer series, the wave number is given by :
![\dfrac{1}{\lambda}=R(\dfrac{1}{n_1^2}-\dfrac{1}{n_2^2})](https://tex.z-dn.net/?f=%5Cdfrac%7B1%7D%7B%5Clambda%7D%3DR%28%5Cdfrac%7B1%7D%7Bn_1%5E2%7D-%5Cdfrac%7B1%7D%7Bn_2%5E2%7D%29)
R is the Rydberg's constant
For Balmer series, n₁ = 2. So,
![\dfrac{1}{\lambda}=1.097\times 10^7\times (\dfrac{1}{2^2}-\dfrac{1}{5^2})](https://tex.z-dn.net/?f=%5Cdfrac%7B1%7D%7B%5Clambda%7D%3D1.097%5Ctimes%2010%5E7%5Ctimes%20%28%5Cdfrac%7B1%7D%7B2%5E2%7D-%5Cdfrac%7B1%7D%7B5%5E2%7D%29)
![\lambda=4.34\times 10^{-7}\ m](https://tex.z-dn.net/?f=%5Clambda%3D4.34%5Ctimes%2010%5E%7B-7%7D%5C%20m)
or
![\lambda=434\ nm](https://tex.z-dn.net/?f=%5Clambda%3D434%5C%20nm)
So, the wavelength of the visible line in the hydrogen spectrum is 434 nm. Hence, this is the required solution.
Answer:
A. Wegener could not explain what made the continents move.
Explanation: