There are 4 questions related to this problem:
1 If the half-life of the drug is 7.3 hours, what fraction of the drug remains in the patient after 24 hours?The amount of the drug is halved every 7.3-hour period, and 24 hours equals 24/7.3 of these halving periods.
So the portion of the drug left over after 24 hours is (1/2) ^ (24/7.3) = 0.10224 2 Write a general expression for the amount of the drug in the patient immediately after taking the nth dose of the drug
One method is to combine the residual amounts from each amount, when the nth dose arises; this will contain adding a finite geometric series
So the total amount of the drug immediately after the nth dose, in mg, is An = 40+ 40(0.10224) + 40(0.10224)^2 + ... + 40(0.10244)^(n-1)
An = 40[1 - (0.010224)^n]/(1 - 0.10224)
3 Write a broad expression for the quantity of the drug in the patient directly before taking the nth dose of the drug
Pn = An – 40
= 40(0.10224) + 40(0.10224)^2 + ... + 40(0.10244)^(n-1)
= 40(0.10224) [1 - (0.10224)^(n-1)]/(1 – 0.10224)
= 4.0895 [1 - (0.10224)^(n-1)]
4 What is the long-term minimum amount of drug in the patient?
= lim n-->infinity of Pn
= lim n-->infinity of 4.0895[1 - (0.10224)^(n-1)]
= 4.0895(1 - 0)
= 4.0895 mg.
Answer: Earth’s internal heat
Explanation:
The energy source for plate tectonics is Earth's internal heat while the forces moving the plates are the ridge push and slab pull gravity forces.
At the initial state: v1 = vf = 0.001053 m
3
/kg, h1 = hf = 467.11 kJ/kg, and s1 = sf = 1.4336 kJ/kgK.
The mass of the water is: m = V/v1 = 0.005/0.001053 = 4.7483 kg.
To find the final state, we will use the First Law:
Q12 = m(h2 - h1) for closed system undergoing a constant pressure process.
h2 = 1Q2/m + h1 = 2200/4.7483 + 467.11 = 930.43 kJ/kg.
At P2 = P1 = 150 kPa, this is a saturated mixture.
hf = 467.11 kJ/kg, hfg = 2226.5 kJ/kg, sf = 1.4336 kJ/kgK, and sfg = 5.7897 kJ/kgK
s2 = sf + sfg (h2 – hf )/hfg = 1.4336 + 5.7897(930.43 – 467.11)/2226.5 = 2.6384 kJ/kgK.
The entropy change of water is:
Delta Ssys= m(s2 – s1) = 4.7483(2.6384 – 1.4336) = 5.72 kJ/K.
Answer:
Produces heat in various parts of machines.
Due to friction we have to exert more power in machines.
It opposes the motion.
Due to friction, noise is also produced in machines.
Due to friction, engines of automobiles consume more fuel which is a money loss.
Explanation:
Source: https://www.quora.com/What-are-the-disadvantages-of-friction
