I need help with this question id really appreciate it thanks !

3. Sodium-24 has a half-life of 15 hours. If a sample of sodium-24 has an

sattari [20]

Answer:

See explanation

Explanation:

From the formula;

0.693/t1/2 = 2.303/t log (Ao/A)

t1/2 = half life of Sodium-24

Ao = initial activity of Sodium-24

A= activity of Sodium-24 at time = t

So,

0.693/15 = 2.303/15 log (800/A)

0.0462 = 0.1535 log (800/A)

0.0462/0.1535 = log (800/A)

0.3 = log (800/A)

Antilog(0.3) = (800/A)

1.995 = (800/A)

A = 800/1.995

A = 401 Bq

ii) 0.693/15 = 2.303/30 log (800/A)

0.0462 = 0.0768 log (800/A)

0.0462/0.0768 = log (800/A)

0.6 = log (800/A)

Antilog (0.6) = (800/A)

3.98 = (800/A)

A = 800/3.98

A = 201 Bq

iii)

0.693/15 = 2.303/45 log (800/A)

0.0462 = 0.0512 log (800/A)

0.0462/0.0512 = log (800/A)

0.9 = log (800/A)

Antilog (0.9) = (800/A)

7.94 = (800/A)

A = 800/7.94

A= 100.8 Bq

iv)

0.693/15 = 2.303/60 log (800/A)

0.0462 = 0.038 log (800/A)

0.0462/0.038 = log (800/A)

1.216 = log (800/A)

Antilog(1.216) = (800/A)

16.44 = (800/A)

A = 800/16.44

A = 48.66 Bq

3 0

3 years ago

A mirror forms an erect image 40cm from the object and one third its height where must the mirror be situated

iragen [17]

The mirror is located 30 cm from the object

Explanation:

To solve the problem, we can use the magnification equation, which states that:

$M=\frac{y'}{y}=-\frac{q}{p}$

where

M is the magnification

y' is the size of the image

y is the size of the object

q is the distance of the image from the mirror

p is the distance of the object from the mirror

In this problem, we notice that the image formed by the mirror is erect and diminished: this means that this is a convex mirror, so the image is virtual, and this means that the image and the object are located on opposite sides of the mirror. Therefore,

$p-q=40 cm$ (distance of the image from the object is 40 cm, but since the image is virtual, q is the negative)

The size of the image is 1/3 that of the object, so

$y'=\frac{1}{3}y$

Solving the equation for p, we find the distance between the object and the mirror:

$\frac{y'}{y}=-\frac{p-40}{p}\\\\p=\frac{40}{1+\frac{y'}{y}}=\frac{40}{4/3}=30 cm$

So, the mirror is 30 cm from the object.

#LearnwithBrainly

5 0

3 years ago

An element consists of two isotopes. The abundance of one isotope is 60.40% and its atomic mass is 68.9257 u. The atomic mass of

amm1812

Answer:

69.7173 u

Explanation:

The abundance of the first isotope is =60.40%

So the abundance of the second isotope =100%-60.40%=39.6%

Atomic mass of first isotope = 68.9257

So the average atomic mass of the first isotope =68.9257×0.6040=41.6311 u

Atomic mass of the second isotope =70.9249 u

So average atomic mass of second isotope =70.9249×0.396=28.086

Now the average atomic mass =41.6311+28.086=69.7173 u

7 0

3 years ago

Read 2 more answers

High-speed stroboscopic photographs show that the head of a 180 g golf club is traveling at 47 m/s just before it strikes a 46 g

inn [45]

Answer:

47 m/s

Explanation:

golf club mass, mc = 180 g

golf ball mass, mb = 46 g

initial golf club speed, vc1 = 47 m/s

final golf club speed, vc2 = 35 m/s

initial golf ball speed, vb1 = 0 m/s

final golf ball speed, vb2 = ? m/s

The total momentum is conserved, then:

mc*vc1 + mb*vb1 = mc*vc2 + mb*vb2

Replacing with data and solving (dimension are omitted):

180*47 + 46*0 = 180*35 + 46*vb2

vb2 = (180*47 - 180*35)/46

vb2 = 47 m/s

7 0

3 years ago

Read 2 more answers

Is direction the length of the route between two points ?

zepelin [54]

Answer:

No distance is the length between two routes

Explanation:

Distance is the length of the route between two points. ... Direction is just as important as distance in describing motion. A vector is a quantity that has both size and direction. It can be used to represent the distance and direction of motion.

6 0

2 years ago