1.

A particle of charge q and mass mmoves rectilinearly under the action of an electric field E = alpha-betax. Here, alpha and beta are positive constants and x is the distance from the point where the particle was initially at rest. Then, the

Answer»

motion of the particle is oscillatory
AMPLITUDE of the particle is `(alpha//beta)`
mean position of the particle is at `X=(alpha//beta)`
maximum acceleration of the particle is `(qalpha)/m`.

Solution :Acceleration of particle,
`a=F/m = (qE)/m=q/m(alpha-betax)` ….(i)
a=0 at x=`alpha/beta`
i.e., force on the particle is ZERO at x= `alpha/beta`
So, mean position of the particle is at x= `alpha/beta`
`v(dv)/(DX)=q/m(alpha-betax)`
`therefore int_0^v vdv=q/mint_0^x (alpha-betax)dx "" therefore v=sqrt((2qx)/m(alpha-beta/2x))`
v=0 at x=0 and `x=(2ALPHA)/beta`
So, the particle oscillates between x=0 and `x=(2alpha)/beta` with mean position at `x=alpha/beta`
Maximum acceleration of the particle is at extreme position (at x=0 or `x=2alpha//beta` and `a_"max"=qalpha//m` [ from equation (i)]


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