An electric toy car with a mass of #6 kg# is powered by a motor with a voltage of #5 V# and a current supply of #7 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 · 2018-05-23T09:21:17

The time is ##=0.61s

The power is

#P=UI#

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

The voltage is #U=5V#

The current is #I=7A#

The power is

#P=UI=5*7=35W#

The kinetic energy of the car is

#E=1/2mv^2#

The mass of the car is #m=6kg#

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

So,

The kinetic energy is

#E=1/2mv^2=1/2*6*(8/3)^2=21.33J#

Let the time #=(t)s#

#E=Pt#

#"Energy=Power" xx "time"#

The time is

#t=E/P=(21.33)/35=0.61s#