Answer:
It will take 7 years ( approx )
Step-by-step explanation:
Given equation that shows the amount of the substance after t years,

Where,
= Initial amount of the substance,
If the half life of the substance is 19 years,
Then if t = 19, amount of the substance =
,
i.e.



Taking ln both sides,



Now, if the substance to decay to 78% of its original amount,
Then 


Again taking ln both sides,



Hence, approximately the substance would be 78% of its initial value after 7 years.
Answer:
P_max = 9.032 KN
Step-by-step explanation:
Given:
- Bar width and each side of bracket w = 70 mm
- Bar thickness and each side of bracket t = 20 mm
- Pin diameter d = 10 mm
- Average allowable bearing stress of (Bar and Bracket) T = 120 MPa
- Average allowable shear stress of pin S = 115 MPa
Find:
The maximum force P that the structure can support.
Solution:
- Bearing Stress in bar:
T = P / A
P = T*A
P = (120) * (0.07*0.02)
P = 168 KN
- Shear stress in pin:
S = P / A
P = S*A
P = (115)*pi*(0.01)^2 / 4
P = 9.032 KN
- Bearing Stress in each bracket:
T = P / 2*A
P = T*A*2
P = 2*(120) * (0.07*0.02)
P = 336 KN
- The maximum force P that this structure can support:
P_max = min (168 , 9.032 , 336)
P_max = 9.032 KN
Answer:
135
Step-by-step explanation:
15/100 × 900 = 15 × 9 = 135
Answer:
Option D doesn't make any sense.
Step-by-step explanation:
D) 7 hours of sleep correspond to an age of 19 years.
That is wrong.
If we use the expression provided
hours = 8 + 0.5*(18 -age)
hours = 8 + 0.5*(18 -19)
hours = 8 + 0.5*(-1)
hours = 7.5
Answer:
n = 12.546
Step-by-step explanation:
to find the value of n we need to transpose
n ÷ 102 = 0.123
n = 0.123 × 102
n = 12.546