Answer: d) 312.5 mg
Explanation:
This problem can be solved using the Radioactive Half Life Formula:
Where:
is the remaining amount of Actinium-226
is the initial amount of Actinium-226
is the time elapsed
is the half life of Actinium-226
Knowing this, let's find
:
1) 211m/s
2)240<span>°
3)759,600m or 759.6 km</span>
Answer:
length of selfie-stick is 1.62 m
Explanation:
Given data
image size h1 = 5 mm = 5 ×
m
focal length = 4 mm = 4 ×
m
distance h2 = 2.032 m
to find out
How long of a selfie-stick
solution
here we find first magnification
that is M = h1 /h2
M = 5 ×
/ 2.032
M = 2.46 ×
and we know M = p/q
so p = Mq = 2.46 ×
q
so we apply lens formula
1/f = 1/p - 1/q
1/ 4 ×
= 1 / 2.46 ×
q - 1/q
q = 1.622 m
so length of selfie-stick is 1.62 m
b. 460.8 m/s
Explanation:
The relationship between the speed of the wave along the string, the length of the string and the frequency of the note is

where v is the speed of the wave, L is the length of the string and f is the frequency. Re-arranging the equation and substituting the data of the problem (L=0.90 m and f=256 Hz), we can find v:

c. 18,000 m
Explanation:
The relationship between speed of the wave, distance travelled and time taken is

where
v = 6,000 m/s is the speed of the wave
d = ? is the distance travelled
t = 3 s is the time taken
Re-arranging the formula and substituting the numbers into it, we find:

Work = Force * distance
= 114 N * 2.21m cos(43)
= 184.3 J