An electric toy car with a mass of #5 kg# is powered by a motor with a voltage of #6 V# and a current supply of #7 A#. How long will it take for the toy car to accelerate from rest to #7 m/s#?

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Answer 1 · 2017-05-26T13:08:25

The time is #=2.92s#

Voltage is #U=6V#

Current is #I=7A#

The power of the motor is

#P=UI=6*7=42W#

Velocity is #v=7ms^-1#

Mass is #m=5kg#

The kinetic energy of the car is

#KE=1/2mv^2=1/2*5*(7)^2=122.5J#

But,

#E=P*t#

The time is #t=(122.5)/42=2.92s#