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If dpdt=12p\frac {dp}{dt}=\frac{1}{2p} dtdp​=2p1​ and p=1p=1p=1 when t=0t=0t=0, then p=3p=3p=3, when t is​
Question

If dpdt=12p\frac {dp}{dt}=\frac{1}{2p}  and p=1p=1 when t=0t=0, then p=3p=3, when t is​

A.

4

B.

8

C.

1

D.

2

Correct option is B

Solution:dpdt=12p,p(0)=1Step 1: Separate the variables2p dp=dtStep 2: Integrate both sides2p dp=dt=>p2=t+CStep 3: Use initial condition p=1 when t=012=0+C=>C=1So the solution is: p2=t+1=>t=p21Step 4: Find t when p=3t=321=91=8Final Answer: (B) t=8\textbf{Solution:}\\ \quad \frac{dp}{dt} = \frac{1}{2p}, \quad p(0) = 1 \\[8pt]\textbf{Step 1: Separate the variables} \\2p \, dp = dt \\[8pt]\textbf{Step 2: Integrate both sides} \\\int 2p \, dp = \int dt \Rightarrow p^2 = t + C \\[8pt]\textbf{Step 3: Use initial condition } p = 1 \text{ when } t = 0 \\1^2 = 0 + C \Rightarrow C = 1 \\[8pt]\text{So the solution is: } p^2 = t + 1 \Rightarrow t = p^2 - 1 \\[8pt]\textbf{Step 4: Find } t \text{ when } p = 3 \\t = 3^2 - 1 = 9 - 1 = 8 \\[10pt]\boxed{\text{Final Answer: (B) } t = 8}

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