1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
S_A_V [24]
3 years ago
9

Iodine 131 half life is 8.0 days. Ten percent of the original sample o his isotope remains after (a) 22.7 days (b) 24.9 days (c)

26.6 days (d) 28.1 days
Physics
1 answer:
Artyom0805 [142]3 years ago
4 0

Answer:

option (c) is correct

Explanation:

Half life of a substance is the time in which the element becomes half of is initial value.

half life, T = 8 days

Amount remaining, N = 10 % of original value

Let the original value is No.

N = 10% of No

N = 0.1 No

Let the time taken is t and the decay constant is λ.

The relation between the decay constant and the half life is given by

\lambda =\frac{0.6931}{T}=\frac{0.6931}{8}=0.08664 per day

Us the equation of radioactivity

N=N_{0}e^{-\lambda t}

0.1N_{0}=N_{0}e^{-0.08664 t}

e^{0.08664 t}=10

Taking natural log on both the sides, we get

0.08664 t = 2.303

t = 26.6 days

You might be interested in
State any two effects of gravitational force​
Dmitry_Shevchenko [17]
Connection to Big Idea about energy: Gravity creates gravitational potential energy. Gravitational energy relies on the masses of two bodies and their distance.

Connection to Big Idea about the universe: Gravitational force is exerted by all objects with mass throughout the Universe. It is what keeps the Earth and the planets in orbit around the Sun, and our Solar System in orbit around the centre of the Milky Way. Gravity is one of the forces involved in the birth of stars, their evolution and finally their death.

Connection to Big Idea about Earth: The gravitational force is responsible for many physical properties of Earth and consequently it affects the existence and the properties of living creatures on it. For instance, the existence, the chemical composition and the structure of Earth’s atmosphere was determined by Earth’s gravitational force.

3 0
3 years ago
Kyle is flying a helicopter at 125 m/s on a heading of 325 o . If a wind is blowing at 25 m/s toward a direction of 240.0 o , wh
frosja888 [35]

Answer:

The resultant velocity of the helicopter is \vec v_{H} = \left(89.894\,\frac{m}{s}, -93.348\,\frac{m}{s}\right).

Explanation:

Physically speaking, the resulting velocity of the helicopter (\vec v_{H}), measured in meters per second, is equal to the absolute velocity of the wind (\vec v_{W}), measured in meters per second, plus the velocity of the helicopter relative to wind (\vec v_{H/W}), also call velocity at still air, measured in meters per second. That is:

\vec v_{H} = \vec v_{W}+\vec v_{H/W} (1)

In addition, vectors in rectangular form are defined by the following expression:

\vec v = \|\vec v\| \cdot (\cos \alpha, \sin \alpha) (2)

Where:

\|\vec v\| - Magnitude, measured in meters per second.

\alpha - Direction angle, measured in sexagesimal degrees.

Then, (1) is expanded by applying (2):

\vec v_{H} = \|\vec v_{W}\| \cdot (\cos \alpha_{W},\sin \alpha_{W}) +\|\vec v_{H/W}\| \cdot (\cos \alpha_{H/W},\sin \alpha_{H/W}) (3)

\vec v_{H} = \left(\|\vec v_{W}\|\cdot \cos \alpha_{W}+\|\vec v_{H/W}\|\cdot \cos \alpha_{H/W}, \|\vec v_{W}\|\cdot \sin \alpha_{W}+\|\vec v_{H/W}\|\cdot \sin \alpha_{H/W} \right)

If we know that \|\vec v_{W}\| = 25\,\frac{m}{s}, \|\vec v_{H/W}\| = 125\,\frac{m}{s}, \alpha_{W} = 240^{\circ} and \alpha_{H/W} = 325^{\circ}, then the resulting velocity of the helicopter is:

\vec v_{H} = \left(\left(25\,\frac{m}{s} \right)\cdot \cos 240^{\circ}+\left(125\,\frac{m}{s} \right)\cdot \cos 325^{\circ}, \left(25\,\frac{m}{s} \right)\cdot \sin 240^{\circ}+\left(125\,\frac{m}{s} \right)\cdot \sin 325^{\circ}\right)\vec v_{H} = \left(89.894\,\frac{m}{s}, -93.348\,\frac{m}{s}\right)

The resultant velocity of the helicopter is \vec v_{H} = \left(89.894\,\frac{m}{s}, -93.348\,\frac{m}{s}\right).

8 0
3 years ago
Use wave equation calculate the speed of sound in the air if frequency of 110 hz has a wave length of 3 m
kirill115 [55]
Answer = 330 m/s

The wave equation is as follows:

Wave speed = wavelength x frequency

The known values are:
Wavelength = 3m
Frequency = 110 Hz

Substitute the known values into the wave equation to find the wave speed.

Wave speed = 3 x 110

Wave speed = 330 m/s
8 0
2 years ago
The minimum number of vectors of unequal magnitude required to
EleoNora [17]

Answer:

d

Explanation:

4 0
3 years ago
In what direction would the particles in this wave move, relative to the direction of wave travel?
Setler79 [48]
Everywhere particles dont stay in one place they move elsewhere
7 0
3 years ago
Read 2 more answers
Other questions:
  • Why are there temperature differences on the moon's surface even though there is no atmosphere present?
    8·1 answer
  • Which side of continents have a colder climate than might be expected?
    9·2 answers
  • You are tossing a ball directly up into the air. Before the ball leaves your hand, you are exerting a force directed against the
    9·1 answer
  • Suppose a rocket ship in deep space moves with constant acceleration equal to 9.8 m/s2, which gives the illusion of normal gravi
    8·1 answer
  • If you measure the amount of work accomplished in a particular time interval, u have measured-
    11·1 answer
  • A horizontal spring is attached to the wall on one end and to a mass on the other end. The mass can slide freely on a frictionle
    11·1 answer
  • An increase in the atomic number____the atomic radius moving from
    8·1 answer
  • A heater has a resistance of 10.0 Ω. It operates on a 12.0 V. What is the current through the resistor?
    11·1 answer
  • How long does it take a 5kW shower to use 25000J of energy?
    7·1 answer
  • What is an example of a form of friction that impedes motion
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!