Answer:
Explanation:
Given that,
Half life = 12years
How long does it take to decompose form 655ppbm to 10ppbm.
Rate of decay is given as
Q=Qo• exp(-λt)
at t=0 Qo=655
Then, Q=10
λ is decay rate and it is
λ= In2 / t½
λ= In2/12
λ=0.05776
Therefore,
Q=Qo• exp(-λt)
10=655exp(-0.05776t)
10/655=exp(-0.05776t)
0.01527=exp(-0.05776t)
Take In of both sides
In(0.01527)=-0.05776t
-4.182=-0.05776t
Then, t=-4.182/-0.05776
t=72.4years
Then the time to decay to 10ppbm is 72 years and 3 months
Or 72 years approximately
Answer:
The Moon's distance from the Earth varies during its orbit
Explanation:
The correct statement is ,The Moon's distance from the Earth varies during its orbit.
Important point regarding moon:
1 .Moon is a natural satellite of the earth.
2. Moon is the fifth largest satellite in solar system.
3.Second densest satellite in solar system.
4.Moon rotates about earth.
5.Moon is an astronomical body .
Answer:
Given:
Initial velocity (u) of the object = 0 m/s (Body starts from rest)
Height above the ground (h) = 36 m
Accelration due to gravity (g) = 10 m/s²
To Find:
Time taken (t) by the object to hit the ground
Explanation:
From equation of motion for object under gravity we have:
Substituting values of h, u & g in the equation we get: