One of the radioactive isotopes that fell on the land and got ...

[saliriagwu]

One of the radioactive isotopes that fell on the land and got into the food chain after the Chernobyl accident was 131I. Its half-life is 8 days.
 
  How long was it, following its deposit on the land, before its radioactivity had fallen to 1/32--about 3--of its initial value?
  A) 16 days
  B) several years
  C) 48 days
  D) 40 days
  E) It is impossible to say, even approximately.

Question 2

A small 175-g ball on the end of a light string is revolving uniformly on a frictionless surface in a horizontal circle of diameter 1.0 m. The ball makes 2.0 revolutions every 1.0 s.
 
  (a) What are the magnitude and direction of the acceleration of the ball? (b) Find the tension force that the string exerts on the ball.

[mochi09]

Answer to Question 1

D

Answer to Question 2

(a) 79.0 m/s2 toward the center of the circle (b) 13.8 N

[saliriagwu]

YES! Correct, THANKS for helping me on my review

[kilada]

Gracias!