An electric toy car with a mass of $4 kg$ is powered by a motor with a voltage of $3 V$ and a current supply of $8 A$ . How long will it take for the toy car to accelerate from rest to $3 m/s$ ?

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Answer 1 · 2016-09-06T10:09:58

It will take $3s$ to accelerate the car.

To accelerate the car to $3m/s$ engine has to do work equal to the car's end kinetic energy:

$W=E_k=(mv^2)/2=(4*3^2)/2=2*9=18 [J]$

Now to find the time we have to calculate the engine's power:

$P=U*I=3*8=24[W]$

Finally to calculate the time we have to divide the work/energy by the power:

$t=W/P=18/24=2/3[s]$

An electric toy car with a mass of 4 kg4 kg is powered by a motor with a voltage of 3 V3 V and a current supply of 8 A8 A. How long will it take for the toy car to accelerate from rest to 3 m/s3 m/s?