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

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Answer 1 · 2018-01-08T14:04:14

The time is #=0.5625s#

The power is

#P=UI#

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

The voltage is #U=2V#

The current is #I=3A#

The power is

#P=UI=2*3=6W#

The kinetic energy of the car is

#E=1/2mv^2#

The mass of the car is #m=3kg#

The speed is #v=3/2ms^-1#

So,

The kinetic energy is

#E=1/2mv^2=1/2*3*(3/2)^2=27/8J#

Let the time #=(t)s#

#E=Pt#

#"Energy=Power" xx "time"#

The time is

#t=E/P=(27/8)/6=0.5625s#