PLEASE, ANSWER ALL 5 QUESTIONS AND ALL PARTS POSSIBLE. EXPRESS ALL ANSWERS IN TH
ID: 3279436 • Letter: P
Question
PLEASE, ANSWER ALL 5 QUESTIONS AND ALL PARTS POSSIBLE.
Explanation / Answer
1. for cartesean coordinates, (x,y,z)
angular momentum = m * (r x v)
now, v = dx i /dt + dy j / dt + dz k /dt [ where i , j and k are unit vectors in x,y and z directions respectively]
and r is position vector r = xi + yj + zk
so L = m*[(xi + yj + zk) x (dx i /dt + dy j / dt + dz k /dt )]
L = m*[i(ydz/dt - zdy/dt) + j(zdx/dt -xdz/dt) + k(xdy/dt - ydx/dt)]
so Lx = m[ydz/dt - zdy/dt]
now in polar coordinates
x = rsin(theta)cos(phi)
y = rsin(theta)sin(phi)
z = rcos(theta)
so, Lx = m[r*sin(theta)sin(phi)*r(-sin(theta)*theta') - r*cos(theta)*r*[sin(theta)cos(phi)*phi' - cos(theta)sin(phi)theta']]
so, Lx = mr^2[-sin^2(theta)sin(phi)(theta') - cos(theta)sin(theta)cos(phi)*phi' + cos^2(theta)sin(phi)theta']
2. Ly = m(zdx/dt - xdz/dt)
substituting
Ly = m[rcos(theta)*r[sin(theta)(-sin(phi))(phi') + cos(theta)cos(phi)(theta')] - rsin(theta)cos(phi)(-rsin(theta)*(theta'))]
Ly = mr^2[-sin(theta)cos(theta)(sin(phi))(phi') + cos^2(theta)cos(phi)(theta') + sin^2(theta)cos(phi)(theta'))]
3. given r and theta = 90 deg, so theta' = 0
Lx = mr^2[-sin^2(theta)sin(phi)(theta') - cos(theta)sin(theta)cos(phi)*phi' + cos^2(theta)sin(phi)theta']
Lx = mr^2[ - cos(90)sin(90)cos(phi)*phi' ] = 0
Ly = mr^2[-sin(theta)cos(theta)(sin(phi))(phi') + cos^2(theta)cos(phi)(theta') + sin^2(theta)cos(phi)(theta'))]
Ly = 0
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