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Sphinxa [80]
4 years ago
12

the half life of a certain substance is 25 years. How long will it take for a sample of this substance to decay to 90% of its or

iginal amount ...?
Physics
1 answer:
Sveta_85 [38]4 years ago
3 0
10% =  1/2 ^n
*where n is number of half lives to reach 10%

n = ln10/ln2

and multiply by 25 gives 83.05 years to 2dp

Hope this helps
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A unit of time sometimes used in microscopic physics is the "shake". One shake equals 10−8 s.
Lady_Fox [76]

Answer:

(a) There are 3.17 times more shakes in a second than seconds in a year.

(b) Humans have existed for 9067.72 universe seconds.

Explanation:

(a) First we calcule how many seconds are in a year. One year have 365 days, one day has 24 hours, one hour has 60 minutes and one minute has 60 seconds, so:

60s*60*24*365=3.1536*10^7s

Now, we calculate how many shakes are in a second:

1s*\frac{1shake}{10^{-8}s}=10^8shakes

Finally, we calculate how many more shakes in a second are there than seconds in a year:

\frac{10^8s}{3.1536*10^7s}=3.17

(b) Using a simple rule of three we can calculate  how many "universe seconds" have humans existed, recall that 1 day has 86400 seconds:

1010 years--------->86400s

106 years----------> x seconds

x=\frac{106y*86400s}{1010y}=9067.72s

3 0
3 years ago
The pitchers mound in baseball is 85 meters from home plate . If it takes 4.1 seconds for a pitch to reach the plate , how fast
adoni [48]

Answer: 20.73m/s

Explanation:

The question simply wants us to calculate the speed of the pitch. The speed will be calculated as:

= Distance/Time

where,

Distance = 85 meters

Time = 4.1 seconds

Speed = Distance/Time

Speed = 85/4.1

Speed = 20.73m/s

Therefore, the speed of the pitch is 20.73m/s.

3 0
4 years ago
PLS HELP BEING TIMED!!!
Elodia [21]

Answer:

K_{i}+U_{g,i} = K_{f}+U_{g,f}

Explanation:

A closed system is a system where exists energy interactions with surroundings, but not mass interactions. If we neglect any energy interactions from boundary work, heat, electricity, magnetism and nuclear phenomena and assume that process occurs at steady state and all effects from non-conservative forces can be neglected, then the equation of energy conservation is reduce to this form:

\Delta K +\Delta U_{g} = 0 (1)

Where:

\Delta K - Change in kinetic energy of the system, measured in joules.

\Delta U_{g} - Change in gravitational potential energy of the system, measured in joules.

If we know that \Delta K=K_{i}-K_{f} and \Delta U_{g} = U_{g,i}-U_{g,f}, then we get the following equation:

K_{i}+U_{g,i} = K_{f}+U_{g,f} (2)

Where i and f stands for initial and final states of each energy component.

Hence, the right answer is K_{i}+U_{g,i} = K_{f}+U_{g,f}

7 0
3 years ago
Read 2 more answers
4. SEP Construct Explanations What type(s) of energy
ziro4ka [17]

Answer:

it is below pls give 5 star

Explanation:

Foods contain stored potential energy in the form of chemical energy. When we consume food, the particles undergo a chemical reaction that releases the chemical energy. In turn, this energy is used by the body to perform its daily activities.

Therefore, when you eat a bowl of vegetable soup, you get the chemical energy that is stored in it.

RESULT

Foods contain stored potential energy in the form of chemical energy. When we consume food, the particles undergo a chemical reaction that releases the chemical energy. In turn, this energy is used by the body to perform its daily activities.

Therefore, when you eat a bowl of vegetable soup, you get the chemical energy that is stored in it

3 0
3 years ago
Match each space mission with the correct milestone.
MrRissso [65]

Matching each space mission with the correct milestone

  1. First animal in space ____________ Sputnik 2
  2. first person in space ____________  Vostok 1
  3. first person on the moon _________  Apollo 11
  4. first man-made object in space ____  Sputnik 1
  5. first American in space __________   Freedom 7
  6. first space station ______________ Salyut

<h3>Meaning of space mission</h3>

A space mission is a mission that takes an individual, animal, a thing or material out of earth using a spaceship. This mission is always carried out with a desire to find out more about the galaxy earth is a member of and to learn about other planets.

In conclusion, the list above is the accurate Matching of each space mission with the correct milestone.

Learn more about Space mission: brainly.com/question/1298543

#SPJ1

6 0
2 years ago
Read 2 more answers
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