An electric toy car with a mass of #6 kg# is powered by a motor with a voltage of #9 V# and a current supply of #3 A#. How long will it take for the toy car to accelerate from rest to #8/3 m/s#?

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Answer 1 · 2017-08-29T14:30:28

The time is #=0.79s#

The power is

#P=UI#

The voltage is #U=9V#

The current is #I=3A#

The power is

#P=UI=9*3=27W#

The kinetic energy of the car is

#E=1/2mv^2#

The mass is #m=6kg#

The speed is #v=8/3ms^-1#

so,

#E=1/2*6*(8/3)^2=64/3J#

Let the time #=(t)s#

#E=Pt#

#t=E/P=(64/3)/27=0.79s#