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

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

An electric toy car with a mass of 2 kg2 kg is powered by a motor with a voltage of 9 V9 V and a current supply of 2 A2 A. How long will it take for the toy car to accelerate from rest to 1/3 m/s1/3 m/s?