Recent content by ebolaformula

Thank you!

Thank you for the answers But there rises another question, why does the position vector has radial component only? Shouldn't it be rr+θθ+ϕϕ? (r,θ,ϕ are unit vectors)

When we obtain the velocity vector for position vector (r, θ, φ) Why do we take the time derivative of the radial part in the 3D Spherical Coordinate system only? Don't we need to consider the polar angle and azimuthal angle part like (dr/dt, dθ/dt, dφ/dt)?