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andrew-mc [135]
2 years ago
10

If the activity of a radionuclide decreases from 5,000 disintegrations per minute to 625 disintegrations per minute

Physics
1 answer:
lys-0071 [83]2 years ago
7 0

Answer:

4 hrs

Explanation:

625 = 5000 (1/2)^n

625/5000 = 1/2^n

n = 3 half lives

3 half lives = 12 hours       1 half life = 4 hrs

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2 years ago
A steam engine absorbs 4 x 105 J and expels 3.5 x 105 J in each cycle. What is its efficiency?
Wewaii [24]
Input heat, Qin = 4 x 10⁵ J
Output heat, Qout = 3.5 x 10⁵ J

From the first Law of thermodynamics, obtain useful work performed as
W = Qin  -  Qout
     = 0.5 x 10⁵ J

By definition, the efficiency is
η = W/Qin
   = 100*(0.5 x 10⁵/4 x 10⁵)
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Answer: The efficiency is 12.5%
3 0
3 years ago
2. Tomas is hanging from a tree limb, that is inclined at a 65° angle. The force
LUCKY_DIMON [66]

Answer:

57 N

Explanation:

Were are told that the force

of gravity on Tomas is 57 N.

And it acts at an inclined angle of 65°

Thus;

The vertical component of the velocity is; F_y = 57 sin 65

While the horizontal component is;

F_x = 57 cos 65

Thus;

F_y = 51.66 N

F_x = 24.09 N

The net force will be;

F_net = √((F_y)² + (F_x)²)

F_net = √(51.66² + 24.09²)

F_net = √3249.0837

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4 0
3 years ago
Ben walks 500 meters from his house to the corner store. He then walks back toward his house but stops to talk to a neighbor whe
spin [16.1K]
Average velocity =

      (displacement) / (time for the displacement)
and
      (direction of the displacement) .

Displacement =

      (distance from the start-point to the end-point)
and
      (direction from the start-point to the end-point)   .

When Ben is 200 meters from the corner store,
he is (500 - 200) = 300 meters from his house.

His displacement is

         300 meters in the direction
                             from his house to the neighbor .


His average velocity is

         (300/910) =  0.33 meters per second, in the
                               direction from his house to the neighbor .


7 0
3 years ago
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