It is helpful to study the light that comes off stars because C. The light from a star gives hints of what elements make up a star.
Answer:
0.191 s
Explanation:
The distance from the center of the cube to the upper corner is r = d/√2.
When the cube is rotated an angle θ, the spring is stretched a distance of r sin θ. The new vertical distance from the center to the corner is r cos θ.
Sum of the torques:
∑τ = Iα
Fr cos θ = Iα
(k r sin θ) r cos θ = Iα
kr² sin θ cos θ = Iα
k (d²/2) sin θ cos θ = Iα
For a cube rotating about its center, I = ⅙ md².
k (d²/2) sin θ cos θ = ⅙ md² α
3k sin θ cos θ = mα
3/2 k sin(2θ) = mα
For small values of θ, sin θ ≈ θ.
3/2 k (2θ) = mα
α = (3k/m) θ
d²θ/dt² = (3k/m) θ
For this differential equation, the coefficient is the square of the angular frequency, ω².
ω² = 3k/m
ω = √(3k/m)
The period is:
T = 2π / ω
T = 2π √(m/(3k))
Given m = 2.50 kg and k = 900 N/m:
T = 2π √(2.50 kg / (3 × 900 N/m))
T = 0.191 s
The period is 0.191 seconds.
Answer:
Part a)
![\alpha = \frac{2(m_1 - m_2)g}{(m_1 + m_2)L}](https://tex.z-dn.net/?f=%5Calpha%20%3D%20%5Cfrac%7B2%28m_1%20-%20m_2%29g%7D%7B%28m_1%20%2B%20m_2%29L%7D)
Part b)
![\alpha = \frac{6(m1 - m_2)g}{3(m_1 + m_2)L + m_{bar}L}](https://tex.z-dn.net/?f=%5Calpha%20%3D%20%5Cfrac%7B6%28m1%20-%20m_2%29g%7D%7B3%28m_1%20%2B%20m_2%29L%20%2B%20m_%7Bbar%7DL%7D)
Explanation:
As we know that the see saw bar is massless so here torque due to two masses is given as
![\tau = I\alpha](https://tex.z-dn.net/?f=%5Ctau%20%3D%20I%5Calpha)
here we will have
![\tau = (m_1g - m_2g)(\frac{L}{2})](https://tex.z-dn.net/?f=%5Ctau%20%3D%20%28m_1g%20-%20m_2g%29%28%5Cfrac%7BL%7D%7B2%7D%29)
now we will have inertia of two masses given as
![I = (m_1 + m_2)(\frac{L}{2})^2](https://tex.z-dn.net/?f=I%20%3D%20%28m_1%20%2B%20m_2%29%28%5Cfrac%7BL%7D%7B2%7D%29%5E2)
now we have
![I = (m_1 + m_2)\frac{L^2}{4}](https://tex.z-dn.net/?f=I%20%3D%20%28m_1%20%2B%20m_2%29%5Cfrac%7BL%5E2%7D%7B4%7D)
now the angular acceleration is given as
![\alpha = \frac{\tau}{I}](https://tex.z-dn.net/?f=%5Calpha%20%3D%20%5Cfrac%7B%5Ctau%7D%7BI%7D)
so we have
![\alpha = \frac{2(m_1 - m_2)g}{(m_1 + m_2)L}](https://tex.z-dn.net/?f=%5Calpha%20%3D%20%5Cfrac%7B2%28m_1%20-%20m_2%29g%7D%7B%28m_1%20%2B%20m_2%29L%7D)
Part b)
Now if the rod is not massles then we will have total inertia given as
![I = (m_1 + m_2)(\frac{L}{2})^2 + \frac{m_{bar}L^2}{12}](https://tex.z-dn.net/?f=I%20%3D%20%28m_1%20%2B%20m_2%29%28%5Cfrac%7BL%7D%7B2%7D%29%5E2%20%2B%20%5Cfrac%7Bm_%7Bbar%7DL%5E2%7D%7B12%7D)
so we will have
![I = (m_1 + m_2)\frac{L^2}{4} + \frac{m_{bar}L^2}{12}](https://tex.z-dn.net/?f=I%20%3D%20%28m_1%20%2B%20m_2%29%5Cfrac%7BL%5E2%7D%7B4%7D%20%2B%20%5Cfrac%7Bm_%7Bbar%7DL%5E2%7D%7B12%7D)
now the acceleration is given as
![\alpha = \frac{\tau}{I}](https://tex.z-dn.net/?f=%5Calpha%20%3D%20%5Cfrac%7B%5Ctau%7D%7BI%7D)
![\alpha = \frac{6(m1 - m_2)g}{3(m_1 + m_2)L + m_{bar}L}](https://tex.z-dn.net/?f=%5Calpha%20%3D%20%5Cfrac%7B6%28m1%20-%20m_2%29g%7D%7B3%28m_1%20%2B%20m_2%29L%20%2B%20m_%7Bbar%7DL%7D)