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
alexgriva [62]
3 years ago
14

If you have 80g of a radioactive substance whose half life is 2 days, how long will it take for the substance to decay to the po

int where there is only 10g left?
Physics
1 answer:
Ber [7]3 years ago
5 0

Answer:

6 days.

Explanation:

From radioactivity, The expression for half life is given as,

R/R' = 2⁽ᵃ/ᵇ)................... Equation 1

Where R = original mass of the radioactive substance, R' = Remaining mass of the radioactive substance after decay, a = Total time taken to decay, b = half life.

Given: R = 80 g, R' = 10 g, b = 2 days.

Substitute into equation 1

80/10 = 2⁽ᵃ/²⁾

8 = 2⁽ᵃ/²⁾

2³ = 2⁽ᵃ/²)

Equating the base and solving for a

3 = a/2

a = 2×3

a = 6 days.

You might be interested in
A python can detect thermal radiation from objects that differ in temperature from their environment as long as the received int
yanalaym [24]

Answer:

10.52 m

Explanation:

The power radiated by a body is given by

P = σεAT⁴ where ε = emissivity = 0.97, T = temperature = 30 C + 273 = 303 K, A = surface area of human body = 1.8 m², σ = 5.67 × 10⁻⁴ W/m²K⁴

P = σεAT⁴ = 5.67 × 10⁻⁸ W/m²K⁴ ×  0.97 × 1.8 m² × (303)⁴ = 834.45 W

This is the power radiated by the human body.

The intensity I = P/A where A = 4πr² where r = distance from human body.

I = P/4πr²

r = (√P/πI)/2

If the python is able to detect an intensity of 0.60 W/m², with a power of 834.45 W emitted by the human body, the maximum distance r, is thus

r = (√P/πI)/2 = (√834.45/0.60π)/2 = 21.04/2 = 10.52 m

So, the maximum distance at which a python could detect your presence is 10.52 m.

3 0
3 years ago
A train travels 55 kilometers in 2 hours, and then 52 kilometers in 5 hours. What is its average speed?
bulgar [2K]

The formula for working out speed is distance ÷ time.

55 km ÷ 2 hours = 27.5 km/h (average speed for first part of journey)

52km ÷ 5 hours = 10.4 km/h (average speed for second part of journey)

(27.5 + 10.4) ÷ 2 = 18.95 km/h (average speed throughout the journey)

4 0
3 years ago
Read 2 more answers
Which statement corresponds to emission spectra?
monitta
B
i just took the test






7 0
3 years ago
Which statement describes the energy transformation that occurs when a person eats a sandwich to gain energy for a long hike? O
Nataly [62]

Answer:chemical energy is transformed into kinetic energy

Explanation:

7 0
3 years ago
PLSS HELP ITS TIMED <br> WILL MARK BRAINLIEST
dlinn [17]

Answer:

tjfd

Explanation:

tuff

4 0
3 years ago
Other questions:
  • What is meant by constructive and destructive interference
    15·1 answer
  • Fiber is an example of a complex carbohydrate true or false
    6·2 answers
  • When a physical change occurs, the mass of the substance is conserved. This means that the total mass of the substance remains t
    5·1 answer
  • Please need help on this I know it’s not D an atom.
    7·1 answer
  • To understand Newton's 1st law. Newton's Principia states this first law of motion: An object subject to no net force maintains
    5·1 answer
  • Power is expressed in ________?
    14·1 answer
  • What is 1.293 metric tons in grams
    14·1 answer
  • . Assume you have a dot grid with 36 dots per sq.in. How many acres are represented by each dot using the following map scales:
    14·1 answer
  • If position vector r = bt^2i + ct^3j, where b and c are positive constants, when does the velocity vector make an angle of 450 w
    10·1 answer
  • Two cars of the same mass collide at an intersection. Just before the collision, one car is traveling east at 80.0 km/h and the
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!