An electric toy car with a mass of #3 kg# is powered by a motor with a voltage of #3 V# and a current supply of #4 A#. How long will it take for the toy car to accelerate from rest to #1 m/s#?

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Answer 1 · 2017-12-05T07:01:46

The time is #=0.125s#

The power is

#P=UI#

The voltage is #U=3V#

The current is #I=4A#

The power is

#P=UI=3*4=12W#

The kinetic energy of the car is

#E=1/2mv^2#

The mass is #m=3kg#

The speed is #v=1ms^-1#

so,

#E=1/2*3*(1)^2=1.5J#

Let the time #=(t)s#

#E=Pt#

#t=E/P=(1.5)/12=0.125s#