An electric toy car with a mass of $3 k g$ $3 kg$ is powered by a motor with a voltage of $8 V$ $8 V$ and a current supply of $5 A$ $5 A$ . 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 · 2016-03-20T02:13:32

$0.6 s$ $0.6 "s"$

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

$P = I V$ $P = IV$

$= (8 V) \cdot (5 A)$ $= (8 "V") * (5 "A")$

$= 40 W$ $= 40 "W"$

The change in kinetic energy for the car is

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

$= 1/2 (3 "kg") ((4 "m/s")^2 - (0 "m/s")^2)$

$= 24 "J"$

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

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

$= frac{24 "J"}{40 "W"}$

$= 0.6 "s"$

An electric toy car with a mass of 3 kg3kg3 kg is powered by a motor with a voltage of 8 V8V8 V and a current supply of 5 A5A5 A. How long will it take for the toy car to accelerate from rest to 4 m/s4ms4 m/s?