Answer:
just-noticeable difference
Explanation:
Using principles of psychology and physics, a branch of experimental psychology called psychophysics has been created. This field is focused on the sensation, the sense and the perception of stimuli. Within this branch it has been called just-noticeable difference to the amount that must be changed of some stimulus so that this difference is noticeable, that is to say, the threshold at which the change is perceived.
Answer:

Explanation:
Given:
- mass of the object,

forces by two mutually perpendicular ropes of the attached to the object:
<u>Now we find the resultant force effect due to the two given forces:</u>



<u>Now the acceleration will be due to this resultant force:</u>



Explanation:
Archimedes' principle states that the upward buoyant force which is exerted on body when immersed whether fully submerged or partially in the fluid is equal to weight of fluid which body displaces and this force acts in upward direction at center of mass of displaced fluid.
Thus,
<u>Weight of the displaced fluid = Weight of the object - Weight of object in fluid.</u>
Density offers a convenient means of obtaining the mass of a body from its volume or vice versa; the mass is equal to the volume multiplied by the density (M = Vd), while the volume is equal to the mass divided by the density (V = M/d).
M = V d
M = 1.4 * 2 = 2.8 kg