A particle is moving along a straight line and has an
acceleration of kV^2 m/s^2, where V is the velocity of the
particle. At time t=0, the velocity of the particle = 4m/s, and the
time t=30s the velocity = 26m/s and displacement at time t = Dt
metres. Derive expressions for both velocity and displacement as a
function of time t.

Respuesta :

Answer with Explanation:

By definition of acceleration  we have

[tex]a=\frac{dv}{dt}[/tex]

Given [tex]a=kv^{2}[/tex], using this value in the above equation we get

[tex]kv^2=\frac{dv}{dt}\\\\\frac{dv}{v^{1}}=kdt[/tex]

Upon integrating on both sides we get

[tex]\int \frac{dv}{v^2}=\int kdt\\\\-\frac{1}{v}=kt+c[/tex]

'c' is the constant of integration whose value can be found out by putting value of 't' = 0 and noting V =4 m/s

Thus [tex]c=-\frac{1}{4}[/tex]

the value of 'k' can be found by using the fact that at t= 30 seconds velocity = 26 m/s

[tex]\frac{-1}{26}=k\times 30-\frac{1}{4}\\\\\therefore k=\frac{\frac{-1}{26}+\frac{1}{4}}{30}\\\\k=7.05\times 10^{-3}[/tex]

Hence the velocity as a function of time is given by

[tex]v(t)=\frac{-1}{7.05\times 10^{-3}t-\frac{1}{4}}[/tex]

By definition of velocity  we have

[tex]v=\frac{dx}{dt}[/tex]

Making use of the obtained velocity function we get

[tex]\frac{dx}{dt}=\frac{-1}{kt-\frac{1}{4}}\\\\\int dx=\int \frac{-dt}{kt-\frac{1}{4}}\\\\x(t)=\frac{-1}{7.05\times 10^{-3}}\cdot ln(7.05\times 10^{-3}t-\frac{1}{4})+x_o[/tex]

here [tex]x_o[/tex] is the constant of integration