An electric toy car with a mass of $5 kg$ is powered by a motor with a voltage of $8 V$ and a current supply of $18 A$ . How long will it take for the toy car to accelerate from rest to $7 m/s$ ?

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Answer 1 · 2017-11-26T13:51:55

The time is $=0.85s$

The power is

$P=UI$

The voltage is $U=8V$

The current is $I=18A$

The power is

$P=UI=8*18=144W$

The kinetic energy of the car is

$E=1/2mv^2$

The mass is $m=5kg$

The speed is $v=7ms^-1$

so,

$E=1/2*5*(7)^2=122.5J$

Let the time $=(t)s$

$E=Pt$

$t=E/P=(122.5)/144=0.85s$

An electric toy car with a mass of 5 kg5 kg is powered by a motor with a voltage of 8 V8 V and a current supply of 18 A18 A. How long will it take for the toy car to accelerate from rest to 7 m/s7 m/s?