# Posts tagged forces

$$\sum_i F_i \cdot \delta r_i$$ is virtual work when internal force is $0$. For that reason, $$\sum_i F_i \cdot \delta r_i = 0$$ Here internal force stands for what? When a object's displacement ...

Mass M1 is held on a plane with inclination angle θ, and mass M2 hangs over the side. The two masses are connected by a massless string which runs over a massless pulley (see Fig. 3.1). The c...

If we have a force which changes depending on the position of a particle, how can we find the position of the particle at some time $t$? We can find its velocity if it has travelled a given distan...