An electric toy car with a mass of #7 kg# is powered by a motor with a voltage of #6 V# and a current supply of #9 A#. How long will it take for the toy car to accelerate from rest to #14/3 m/s#?

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Answer 1 · 2017-12-06T06:20:09

The time is #=0.47s#

The power is

#P=UI#

The voltage is #U=6V#

The current is #I=9A#

The power is

#P=UI=6*9=54W#

The kinetic energy of the car is

#E=1/2mv^2#

The mass is #m=7kg#

The speed is #v=14/3ms^-1#

so,

#E=1/2*7*(14/3)^2=25.28J#

Let the time #=(t)s#

#E=Pt#

#t=E/P=(25.28)/54=0.47s#