At time t = 0 a particle start

Question

At time t = 0 a particle starts moving along the x axis. If its kinetic energy increases uniformly with t the net force acting on it must be:

A. constant

B. proportional to t

C. inversely proportional to t

D. proportional to 根號t

E. proportional to 1/根號t

Answer 1

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Answer:E

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2009-11-03 04:38:38 補充：

k,c=const.

T=kt=(0.5)mv^2 kinetic energy

v=(2kt/m)^0.5 speed_function of t

F=ma=m(dv/dt)=(k(2k/m)^(-0.5))t^(-0.5)

c=k(2k/m)^(-0.5)=const.

F=ct^(-0.5)