An electric toy car with a mass of $7 k g$ $7 kg$ is powered by a motor with a voltage of $1 V$ $1 V$ and a current supply of $6 A$ $6 A$ . How long will it take for the toy car to accelerate from rest to $6 \frac{m}{s}$ $6 m/s$ ?

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Answer 1 · 2016-03-20T02:14:56

$21 s$ $21 "s"$

The power input is the product of the voltage and the current.

$P = I V$ $P = IV$

$= (1 V) \cdot (6 A)$ $= (1 "V") * (6 "A")$

$= 6 W$ $= 6 "W"$

The change in kinetic energy for the car is

$Delta "KE" = 1/2 m (v^2 - v_0^2)$

$= 1/2 (7 "kg") ((6 "m/s")^2 - (0 "m/s")^2)$

$= 126 "J"$

Thus, the time needed is the energy divided by the power.

$t = frac{Delta "KE"}{P}$

$= frac{126 "J"}{6 "W"}$

$= 21 "s"$

An electric toy car with a mass of 7 kg7kg7 kg is powered by a motor with a voltage of 1 V1V1 V and a current supply of 6 A6A6 A. How long will it take for the toy car to accelerate from rest to 6 m/s6ms6 m/s?