The mass of a radioactive element at time t is given by
where
is the mass at time zero, while 
is the half-life of the element.
In our problem,
, t=121.0 s and 
, so we can find the initial mass :
where
In our problem,
What's the speed of a sound wave through water at 25 Celsius
1 answer:
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Hello!
We can use the kinematic equation:
a = acceleration (m/s²)
vf = final velocity (45 m/s)
vi = initial velocity (25 m/s)
t = time (5 sec)
Plug in the givens: