How many times did the original sample lose 50% of its radioactivity ?
-- Start with. . . . . . . . . . . . 12 grams.
-- Lose half of it once. . . . . . 6 grams left.
-- Lose half of it again . . . . . 3 grams left.
-- Lose half of it again . . . . . 1.5 grams left.
-- Lose half of it again . . . . . 0.75 gram left.
-- How many times did it lose half ? 4 times.
-- How long does it take to lose half ? 4.5 days.
(That's why it's called the 'half-life'.)
-- How long did it take to lose half, 4 times ?
(4 x 4.5 days) = 18 days .
<span>this is a dynamometer</span>
In general, surface tension decreases when temperature increases because cohesive forces decrease with an increase of molecular thermal activity. The influence of the surrounding environment is due to the adhesive action of liquid molecules that they have at the interface.
Answer:
c.
Explanation:
We are given that
Acceleration due to gravity on the moon=
Acceleration due to gravity on the earth=
Net force due to am on an object on moon=
There is no friction and no drag force and there is no gravity involved
Then, the force acting on an object on earth=
(given)
Hence, option c is true.
Answer:
The answer is the 1st one
