Recent content by kyiydnlm

  1. K

    High School Apparent Suspension of Gravity

    you need to show us top end of the box.
  2. K

    Moving Ball on sloping surface issue

    r_normal is unit normal vector of your flat square. F_support is force on the ball by the flat square. F_equavilent is equavilent force applied on the ball. M_r is rotational matrix. theta_x, theta_y, theta_z are rotation angle about x, y, and z axis respectively. look, support force on...
  3. K

    Undergrad Understanding Viscosity and Its Relation to Friction in Fluid Mechanics

    OK, you can think about it this way. If you put a box on a smooth surface and a same box on a rough surface. and you push them with same force, which one moves faster? or you try to keep them with same speed, which one needs larger force? now, put two boxes on same surface, but one surface is...
  4. K

    What Acceleration Will the System Move With?

    draw free-body diagrams first; then you will find the answer by yourself.
  5. K

    Moving Ball on sloping surface issue

    hi, chadlee88, try vector if you do not want too much trouble, especially when you are programming. \left[\begin{array}{c}M_{r}\end{array}\right] = \left[\begin{array}{ccc}1&0&0\\0&cos(\theta_{x})&-sin(\theta_{x})\\0&sin(\theta_{x})&cos(\theta_{x})\end{array}\right]...
  6. K

    Differential equation of spring-mass system attached to one end of seesaw

    \frac{L^2}{4} \theta K+J\ddot{\theta} = 0 J = \frac{1}{12}ML^2 case 1: K = K1 case 2: K = K1+K2 Assuming uniform seesaw, pivot is center of mass (also geometry center). If otherwise seesaw is not uniform, J will change accordingly. If pivot is not geometry center, the equation will be...
  7. K

    Missile Landing Radius Problem (Orbital mechanics)

    If you replace g by \frac{GM}{r^2}, things become much easier.
  8. K

    Rotational Dynamics-Moment of inertia

    of course, you can always use its definition: I = \int_{M} r^2dm
  9. K

    Rotational Dynamics-Moment of inertia

    L_{B} = 0.2m (distance between center of mass and axis if you use moment of inertia on center) I = \frac{1}{12}ML^2 + M(0.2)^2
  10. K

    Undergrad Mohr's Circle and understanding its maximums and minimums

    On the pic you provided, ignore the bottom element and let's say index 1 to 4 from left to right. 1 and 3 are on exactly same plane; they are same thing. 2 and 4 on same plane, they are identical. The stresses of each of the pairs are in same direction. 2 and 4 are on principle plane; maximum...
  11. K

    High School Why Does the Acceleration Formula Work?

    hi, staetualex, take a little time on chain rules. It's not dx^2/dv; it's vdv/dx.
  12. K

    Undergrad Solving Mohr's Circle: Deriving Principal Stresses & Strains

    Since you can find 2\varphi, the angle between principle stress and normal stress is \varphi. If you draw your mohr's cicle, the rest will be only a metter of rotating \varphi degress from horizontal axis to find principle stress direction. In geometry, round angle is half of centre angle...