An electric toy car with a mass of $4 kg$ is powered by a motor with a voltage of $2 V$ and a current supply of $7 A$ . How long will it take for the toy car to accelerate from rest to $2 m/s$ ?

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Answer 1 · 2017-03-05T17:05:58

$0.54s$

The energy supplied is calculated by

$E = 1/2mv^2 = 1/2 xx 4 xx 2^2 = 8J$

Electrical power is

$P = IV$

and mechanical power is

$P = E/t$

so we can say that

$E/t = IV$

The question is asking for $t$ , so rearrange

$t = E/(IV) = 8/(2xx7) = 0.54s$

An electric toy car with a mass of 4 kg4 kg is powered by a motor with a voltage of 2 V2 V and a current supply of 7 A7 A. How long will it take for the toy car to accelerate from rest to 2 m/s2 m/s?