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tiny-mole [99]
3 years ago
6

Calcium-51 has a half-life of 4.5 days. Only 0.75 gram remains of a sample that was initially 12 grams. How old is the sample of

calcium-51?
Physics
2 answers:
Over [174]3 years ago
6 0
How many times did the original sample lose 50% of its radioactivity ?

-- Start with. . . . . . . . . . . . 12 grams.
-- Lose half of it once. . . . . . 6 grams left.
-- Lose half of it again . . . . . 3 grams left.
-- Lose half of it again . . . . . 1.5 grams left.
-- Lose half of it again . . . . . 0.75 gram left.

-- How many times did it lose half ?    4 times.

-- How long does it take to lose half ?  4.5 days. 
                                                       (That's why it's called the 'half-life'.)

-- How long did it take to lose half, 4 times ?

                                           (4 x 4.5 days) = 18 days .
tatiyna3 years ago
3 0

Answer:

18 days

Explanation:

You might be interested in
A flat coil of wire consisting of 15 turns, each with an area of 40 cm 2, is positioned perpendicularly to a uniform magnetic fi
zheka24 [161]

Answer:

0.54 A

Explanation:

Parameters given:

Number of turns, N = 15

Area of coil, A = 40 cm² = 0.004 m²

Change in magnetic field, ΔB = 5.1 - 1.5 = 3.6 T

Time interval, Δt = 2 secs

Resistance of the coil, R = 0.2 ohms

To get the magnitude of the current, we have to first find the magnitude of the EMF induced in the coil:

|V| = |(-N * ΔB * A) /Δt)

|V| = | (-15 * 3.6 * 0.004) / 2 |

|V| = 0.108 V

According to Ohm's law:

|V| = |I| * R

|I| = |V| / R

|I| = 0.108 / 0.2

|I| = 0.54 A

The magnitude of the current in the coil of wire is 0.54 A

6 0
3 years ago
Which formula is used to find an object’s acceleration?
marissa [1.9K]

Answer:

Δv/Δt

Explanation:

I beat your game SAW.

8 0
3 years ago
Which of the following is not considered a major work flow structure?
mixas84 [53]

Answer:

The correct option is;

D. Fabrication

Explanation:

A workflow flow is a detailed business process consisting of a series of required interconnected tasks in  directed graph format  that is executable by  workflow management system.

Considering each of the options, we have

A. Work center

This consists of part of the transformation input to output. The location

B. Project

This is the unique identifier of the task to be processed

C. Assembly line

Forms part of the required input where transformation takes place and items are being processed within the assembly line

D. Fabrication

Here the item is fixed, without motion, therefore this is not considered a major work flow structure

E. Continuous flow

Here again, the items are being processed and are in motion, which constitutes a workflow structure.

8 0
3 years ago
Given the two sets, which statement is true?<br><br> A = {1, 2}<br> B = {1, 2, 3, 4}
Mnenie [13.5K]
What are the two sets? I only see the two answers?
3 0
3 years ago
It's not D
DanielleElmas [232]
A. it provides support
5 0
2 years ago
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