19 points! ! a 3.0-kg block is pushed 7.8 m through a rough horizontal surface by a horizontal force of 20.0 n. if the coefficient of kinetic friction between the block and the surface is 0.30, what is the change in kinetic energy of the block (in joules)?

An object of dimensions 50 cm x 40 cm x 0.20 cm has a mass 60g. find its density in g/cm3 and kg/ m3

Awave is produced in a rope. the wave has a speed of 33 m/s and a frequency of 22 hz.

Consider a uniformly charged ring in the xy plane, centered at the origin. the ring has radius a and positive charge qdistributed evenly along its circumference. a)what is the direction of the electric field at any point on the z axis? . b)what is the magnitude of the electric field along the positive z axis? use k in your answer, where k=14πϵ0. d)the ball will oscillate along the z axis between z=d and z=−d in simple harmonic motion. what will be the angular frequency ω of these oscillations? use the approximation d≪a to simplify your calculation; that is, assume that d2+a2≈a2. express your answer in terms of given charges, dimensions, and constants