Describe the structure and working methods of a barometer in short

What are similarities and differences of reflection, refraction, diffraction and absorption?

Asmall object with mass 0.200 kg swings back and forth on the lower end of a light rope that is 3.00 m long. the upper end of the rope is attached to the ceiling. as the object swings through its lowest position, where the rope is vertical, the speed of the object is 5.80 m/s. at this point in the motion, what is the tension in the rope? (use g = 9.80 m/s2.)

Ihave a density of 1.61g/cm^3 and a mass of 28g. find the missing value