An electric toy car with a mass of $5 k g$ $5 kg$ is powered by a motor with a voltage of $11 V$ $11 V$ and a current supply of $5 A$ $5 A$ . How long will it take for the toy car to accelerate from rest to $3 \frac{m}{s}$ $3 m/s$ ?

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Answer 1 · 2016-03-19T04:04:19

$0.409 s$ $0.409 "s"$

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

$P = I V$ $P = IV$

$= (11 V) \cdot (5 A)$ $= (11 "V") * (5 "A")$

$= 55 W$ $= 55 "W"$

The change in kinetic energy for the car is

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

$= 1/2 (5 "kg") ((3 "m/s")^2 - (0 "m/s")^2)$

$= 22.5 "J"$

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

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

$= frac{22.5 "J"}{55 "W"}$

$= 0.409 "s"$

An electric toy car with a mass of 5 kg5kg5 kg is powered by a motor with a voltage of 11 V11V11 V and a current supply of 5 A5A5 A. How long will it take for the toy car to accelerate from rest to 3 m/s3ms3 m/s?