An electric toy car with a mass of $7 kg$ is powered by a motor with a voltage of $2 V$ and a current supply of $2 A$ . How long will it take for the toy car to accelerate from rest to $7 m/s$ ?

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Answer 1 · 2017-03-24T07:25:56

The time is $=42.9s$

Voltage is $U=2V$

Current is $I=2A$

The power is

$P=UI=2*2=4W$

Velocity is $v=7ms^-1$

Mass is $m=7kg$

The kinetic energy is

$KE=1/2mv^2=1/2*7*7^2=171.5J$

But,

$E=P*t$

The time is $t=E/P=171.5/4=42.9s$

An electric toy car with a mass of 7 kg7 kg is powered by a motor with a voltage of 2 V2 V and a current supply of 2 A2 A. How long will it take for the toy car to accelerate from rest to 7 m/s7 m/s?