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
inysia [295]
3 years ago
7

A paleontologist estimates that when a particular rock formed, it contained 12 mg of the radioactive isotope potassium-40, which

has a half-life of 1.26 billion years. The rock now contains 3 mg of the isotope. About how old is the rock? Enter in billions of years.
Physics
1 answer:
leva [86]3 years ago
7 0

Answer:

t = 2.52 billion \:years

Explanation:

As we know by radioactivity law

N = N_o e^{-\lambda t}

so here we will have

N = 3 mg

N_o = 12 mg

now we will have

3 = 12 e^{-\lambda t}

\lambda t = ln 4

now we also know that

\lambda = \frac{ln2}{1.26 \times 10^6 yrs}

t = 1.26\times 10^6\times \frac{ln4}{ln2}

t = 2.52 billion \:years

You might be interested in
Why environmental science is about social action​
stepan [7]

Answer:

<h3>Environmental social science is the application of social science – broadly the study of the relationship between individuals in their context within society – and its application to our understanding of environmental issues.</h3>

Explanation:

<h3>mark as brainliast</h3><h3>indian genius sarthak</h3>
7 0
3 years ago
A boat has a mass of 54,000 kg. The boat is accelerating at 0.4 m/s2. What is the net force acting on the boat?'
Arlecino [84]

Answer:

21.6 kN

Explanation:

F = m * a

F = 54 000 * .4  = 21600 N

5 0
3 years ago
During a race, a runner runs at a speed of 6 m/s. 2 seconds later, she is running at a speed of 10 m/s. What is the runner’s acc
Lina20 [59]
V o = 6 m/s,
t = 2 s
v = 10 m/s
v = v o + a t
a t = v - v o
a = ( v - v o ) / t 
a = ( 10 m/s - 6 m/s ) / 2 s = 4 m/s / 2 s = 2 m/s²
Answer:
The runner`s acceleration is 2 m/s².
6 0
3 years ago
Compare and contrast aerobic physical activity with anaerobic physical activity.
neonofarm [45]

Answer: ompare and contrast aerobic physical activity with anaerobic physical activity. ... Aerobic physical activity is better for the cardiovascular system than it is for strength endurance, while anaerobic physical activity is better at building strength endurance than it is at increasing cardiorespiratory fitness.

Explanation: hopefully this helped ;)

8 0
3 years ago
Read 2 more answers
An electric motor is connected to a battery. The current flows through brushes to a commutator ring, which is attached to a elec
Rzqust [24]

Answer:

Commutator is a ring which reverse the direction of current in AC circuit so that the coil connected to it will continuous to move in the same direction.

Explanation:

In motors there exist a coil which is rotated due to torque of magnetic field when current flow through it. Since AC current is used to run the motor so we know that AC current changes its direction after half cycle.

So here commutator plays an important role to reverse the direction of current after every half cycle so that the current goes in same direction always into the coil.

This will produce a constant direction torque on the coil so that it will rotate in same sense always.

So commutator role is to provide same direction current to the coil by reversing its direction after every half cycle

8 0
3 years ago
Other questions:
  • A fireman standing on a 15 m high ladder
    12·1 answer
  • "In a pure substance all the particles must be identical; therefore pure substances are composed only of elements." Do you agree
    15·1 answer
  • • orange in color what kind of fungi is this
    6·1 answer
  • A parachutist bails out and freely falls 62 m. Then the parachute opens, and thereafter she decelerates at 2.5 m/s2. She reaches
    13·1 answer
  • What is the average acceleration of a car that starts from
    12·2 answers
  • A typical loaded commercial jet airplane has an inertia of 2.3×105 kg
    8·1 answer
  • If you get a job that pays $12 per hour and work 35 hours a week, how much will you make in a year?
    12·1 answer
  • ; (b) A uniform beam 150cm long weighs 3.5kg and
    15·1 answer
  • Marcus tries to move a refrigerator but can't. Has he done work?
    11·1 answer
  • If a train going 60 m/s hits the brakes, and it takes the train 85 seconds to stop, what is
    10·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!