Why is the following situation impossible? Two identical dust particles of mass 1 μg are
floating in empty space, far from any external sources of large gravitational or electric
fields, and at rest with respect to each other. Both particles carry electric charges that are
identical in magnitude and sign. The gravitational and electric forces between the particles
happen to have the same magnitude, so each particle experiences zero net force and the
distance between the particles remains constant.

Ablock of mass m = 2.5 kg is attached to a spring with spring constant k = 710 n/m. it is initially at rest on an inclined plane that is at an angle of θ = 23° with respect to the horizontal, and the coefficient of kinetic friction between the block and the plane is μk = 0.19. in the initial position, where the spring is compressed by a distance of d = 0.16 m, the mass is at its lowest position and the spring is compressed the maximum amount. take the initial gravitational energy of the block as zero. a) what is the block's initial mechanical energy? b) if the spring pushes the block up the incline, what distance, l, in meters will the block travel before coming to rest? the spring remains attached to both the block and the fixed wall throughout its motion.

The crank oa rotates in the vertical plane with a constant clockwise angular velocity ω0 of 5.6 rad/s. for the position where oa is horizontal, calculate the force under the light roller b of the 10.6-kg slender bar ab.

Work = force × a. work b. energy c. distance d. momentum