harmyder
- 31
- 1
Homework Statement
Lecturer says that:
Generalized Coordinate: θ = q1
Generalized Force: Q1 = 0
I don't understand why Q1 equals to zero.
Homework Equations
Q_i = \sum_j \underline F_j \frac{\delta \underline r_j}{\delta q_i}
The Attempt at a Solution
First i need to find partial derivatives:
\frac{\delta \hat x}{\delta q_1} = \frac{\delta \theta r}{\delta \theta}= r (i have lost vector here, but i don't know where to put it in \theta r)
\frac{\delta \hat y}{\delta q_1} = \frac{\delta r}{\delta \theta} = 0 (same here)
Now forces at x and y directions:
F_x \frac{\delta \hat x}{\delta q_1} = -F + m\bf g \sin\psi
F_y \frac{\delta \hat y}{\delta q_1} = N - m\bf g \cos\psi
Now add them:
Q_1 = r (-\bf F + m\bf g \sin\psi) is it zero?