4.2 a beta-emitting radioactive isotope called iodine-131 is often released into the air during nuclear
accidents. it can settle on skin and clothing and can be inhaled or ingested. iodine is absorbed in
the body by the thyroid gland, where it is used to make molecules that travel throughout the body.
when the thyroid gland has enough iodine, any excess iodine is removed by the body. if a nuclear
accident occurs at a power plant, workers are asked to ingest potassium iodide tablets which
contain a stable isotope of iodine. explain how this minimises the risk of damage to their bodies.

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2