An electric toy car with a mass of #2 kg# is powered by a motor with a voltage of #9 V# and a current supply of #2 A#. How long will it take for the toy car to accelerate from rest to #1/3 m/s#?

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Answer 1 · 2017-12-29T06:21:40

The time is #=0.006s#

The power is

#P=UI#

#"Power"="Voltage"xx"Current"#

The voltage is #U=9V#

The current is #I=2A#

The power is

#P=UI=9*2=18W#

The kinetic energy of the car is

#E=1/2mv^2#

The mass is #m=2kg#

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

so,

#E=1/2*2*(1/3)^2=1/9J#

Let the time #=(t)s#

#E=Pt#

The time is

#t=E/P=(1/9)/18=0.006s#