An electric toy car with a mass of $15 k g$ $15 kg$ is powered by a motor with a voltage of $8 V$ $8 V$ and a current supply of $3 A$ $3 A$ . How long will it take for the toy car to accelerate from rest to $4 \frac{m}{s}$ $4 m/s$ ?

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Answer 1 · 2017-03-05T15:58:45

$t = 5 s$ $t=5s$

Electrical power is given by

$P = I V$ $P=IV$

and mechanical power by

$P = \frac{E}{t}$ $P = E/t$

so

$\frac{E}{t} = I V$ $E/t = IV$

We can calculate the kinetic energy, $E$ $E$ , by

$E = \frac{1}{2} m v^{2} = \frac{1}{2} \times 15 \times 4^{2} = 120 J$ $E = 1/2mv^2 = 1/2 xx 15 xx 4^2 = 120J$

The question is asking about time, so

$t = \frac{E}{I V} = \frac{120}{8 \times 3} = 5 s$ $t = E/(IV) = 120/(8xx3) = 5s$

An electric toy car with a mass of 15kg15 kg is powered by a motor with a voltage of 8V8 V and a current supply of 3A3 A. How long will it take for the toy car to accelerate from rest to 4ms4 m/s?