W= 20 N
exerted force= 5N
Normal Force= W – exerted force sin 30°
Normal Force= 20 N – 5 N sin 30°
Normal Force= 20 N – 5 N (0.5)
Normal Force= 20 N – 2.5 N
Normal Force= 17.5 N
the time taken for the radioactivity of a specified isotope to fall to half its original value.
"iodine-131 has a half-life of 8.1 days"
the time required for any specified property (e.g. the concentration of a substance in the body) to decrease by half.