We know that photons (light) are massless but they have momentum. Now suppose I am in the space far away from planets/stars that there is no external force exerts on me, if: 1- I turn on a flashlight (torch), would I be pushed in the opposite direction which the flashlight is facing (Newton's thi...

The first law states that $\text{d}Q = \text{d}W + \text{d}U$ where $\text{d}W$ is the work done by the system on the surroundings. As far as I remember from my chemistry courses,first law in chemistry is $\text{d}U= \text{d}Q + \text{d}W$ where $\text{d}W$ is the work done by the surroundings on...

A perfectly inelastic collision is one where both of the colliding objects stick together and move as one. My questions is, why, of all possible combinations of final velocities that conserve momentum, does this one lead to greatest loss in kinetic energy? One of the reasoning I found was that th...