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A particle of mass m is acted upon by a force F given by the empirical law F=R/(t²)v(t). If this law is to be tested experimentally by observing the motion starting from rest, the best way is to plot

Asked in JEE Main Online 2016 · Position- and velocity-dependent forces

Answer: (1) log v(t) against 1/t

Step-by-step solution

Idea: integrate the law, then look for the pair of variables that leaves a straight line.

m(dv)/(dt)=R/(t²)v, and separating the variables,

(dv)/v=R/m(dt)/(t²).

Integrating both sides,

ln v=-R/m·1/t+C.

That is of the form y=mx+c with y=log v and x=1/t, so those are the axes that give a straight line — and its slope then measures R/m.

The minus sign in front means the line slopes downward, which is also a useful check on the data.

Why the other options are wrong

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