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alexgriva [62]
3 years ago
11

After two hours, 1/16 of the initial amount of a certain radioactive isotope remains undecayed. The half-life of the isotope is:

Physics
1 answer:
AlekseyPX3 years ago
7 0
The half life is 30 minutes.
30 mins- 1/2 left
60 mins- 1/4 left
90 mins- 1/8 left
120 mins- 1/16 left
120 mins= 2 hours
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Light of wavelength 623.0 nm is incident on a narrow slit. The diffraction pattern is viewed on a screen 76.5 cm from the slit.
Dvinal [7]

Answer:

Explanation:

wave length of light λ = 623 x 10⁻⁹ m .

Distance of screen D = 76.5 x 10⁻² m

width of slit        =      d

Distance on the screen between the second order minimum and the central maximum       =  2  λ D / d

1.11 x 10⁻²  = (2 x 623 x 10⁻⁹ x 76.5 x 10⁻² )/ d

d =  ( 2 x 623 x 10⁻⁹ x 76.5 x 10⁻²) / 1.11 x 10⁻²

= 85872.97 x  10⁻⁹

=  85.87297 x  10⁻⁶

= 85.87 μm

width a of the slit is = 85.87 μm

6 0
3 years ago
What are non-contact forces please include example in your answer
Alina [70]

Answer:

Gravitational force.  Magnetic force.  Electrostatics.  Nuclear force.

Explanation:

Apple falling from a tree

raindrops falling from the sky

4 0
3 years ago
Read 2 more answers
__________ is a developmental defect in which a portion of the spinal cord protrudes outside the vertebrae.
7nadin3 [17]

Answer: Spina bifida

Explanation:

Spina bifida is a developmental defect in which a portion of the spinal cord protrudes outside the vertebrae.

Spina bifida is a birth defect that occurs when there is improper formation of the spine and spinal cord. It's a type of neural tube defect. The structure in a developing embryo that eventually becomes the baby's brain, spinal cord and the tissues that enclose them is the neutral tube.

3 0
3 years ago
Please any one have a clue on this one? Really need help on this
lana66690 [7]
Oxygen and Neon have the same number of valence electrons because both the compounds are in the same group and the outer orbital of both the compounds consists of 6 electrons
5 0
3 years ago
A 21 N block rests on a horizontal surface. The coefficients of static and kinetic friction between the surface and the block ar
Georgia [21]

Answer:

a)15 N

b)12.6 N

Explanation:

Given that

Weight of block (wt)= 21 N

μs = 0.80 and μk = 0.60

We know that

Maximum value of static friction given as

Frs = μs m g = μs .wt

by putting the values

Frs= 0.8 x 21 = 16.8 N

Value of kinetic friction

Frk= μk m g = μk .wt

By putting the values

Frk= 0.6 x 21 = 12.6 N

a)

When T = 15 N

Static friction Frs= 16.8 N

Here the value of static friction is more than tension T .It means that block will not move and the value of friction force will be equal to the tension force.

Friction force = 15 N

b)

When T= 35 N

Here value of tension force is more than maximum value of static friction that is why block will move .We know that when body is in motion then kinetic friction will act on the body.so the value of friction force in this case will be 12.6 N

Friction force = 12.6 N

8 0
3 years ago
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