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zhuklara [117]
3 years ago
11

The activity of a radioisotope is found to decrease 40% of its original value in 2.59 x 10 s.

Physics
1 answer:
Rainbow [258]3 years ago
8 0

Answer: 0.0353\ s^{-1}

Explanation:

Given

Radioactive material is found to decrease 40% of its original value in 2.59\times 10\ s

Sample at any time is given by

N=N_oe^{-\lambda t}

where, \lambda=\text{decay constant}

Put values

\Rightarrow 0.4N_o=N_oe^{-\lambda\cdot 2.59\times 10}\\\Rightarrow 0.4=e^{-\lambda\cdot 2.59\times 10

Taking natural logarithm both side

\Rightarrow \lambda=\dfrac{\ln 2.5}{25.9}\\\\\Rightarrow \lambda =0.0353\ s^{-1}

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4 years ago
Steam enters an adiabatic turbine at 6 MPa, 600 ℃, and 80 m/s and leaves at 50 kPa, 100 ℃, and 140 m/s. If the power output of t
lisabon 2012 [21]

Answer:

W(r,out) = 5.81 MW

\eta = 86.1 %

Explanation:

we use here steam table for get value of h1, s1 etc

so use for 6MPa and 600 degree

Enthalphy of steam h1 = 3658.8 kJ/kg

Entropy of steam s 1 is = 7.1693 kJ /kg.K

and

for 50 kPa and 100 degree

Enthalphy of steam h2 = 2682.4 kJ/kg

Entropy of steam s2 is = 7.6953 kJ /kg.K

so we use here energy balance equation that is

m\times(h1 + \frac{v1^2}{2} = m\times(h2 + \frac{v2^2}{2} + W(out)      ..............1

put here value and we get m

m = \frac{5\times1000}{3658.8-2682.4+\frac{80^2-140^2}{2}\times \frac{1}{1000}}  

solve it we get

m = 5.156 kg/s

so by energy balance equation

m\psi1 = m\psi2 + W(r,out)

W(r,out) = m(\psi1 -\psi2)

W(r,out) = h1 - h2 + ΔKE + ΔPE - To(s1-s2)

W(r,out) = m[h1-h2+ \frac{v1^2-v^2}{2}- To (s1-s2)

W(r,out) = W(a,out) - m.To.(s1-s2)     ........................2

put here value

W(r,out) = 5000 - ( 5.156 × (25 + 273) ×( 7.1693 - 7.6953)

W(r,out) = 5908.19 = 5.81 MW

and

second law deficiency is

\eta = \frac{W(a,out)}{W(r,out)}     ..............................3

put here value

\eta = \frac{5}{5.81}

\eta = 86.1 %

6 0
3 years ago
a car travels West 50km for 2 hours before heading south at a rate of 30 km per hour for 1.5 hours. What is the car's average sp
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Answer:

Explanation:

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3 years ago
Resultant of a pair of 100 km/h velocity vectors that are at right angels to each other
nignag [31]

The resultant of the two vectors is 141 km/h.

Explanation:

When two vectors are at right angles to each other, their resultant can be calculated by using the Pythagorean's theorem:

R=\sqrt{A^2+B^2}

where

A is the magnitude of the first vector

B is the magnitude of the second vector

In this problem, we have two velocity vectors of magnitude

A = 100 km/h

B = 100 km/h

Substituting into the formula, we find their resultant:

R=\sqrt{100^2+100^2}=141.4 km/h

Learn more about vector addition here:

brainly.com/question/4945130

brainly.com/question/5892298

#LearnwithBrainly

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