An electric toy car with a mass of $2 k g$ $2 kg$ is powered by a motor with a voltage of $12 V$ $12 V$ and a current supply of $6 A$ $6 A$ . How long will it take for the toy car to accelerate from rest to $\frac{4}{5} \frac{m}{s}$ $4/5 m/s$ ?

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Answer 1 · 2017-05-02T06:32:10

The time is $= 0.009 s$ $=0.009s$

Voltage is $U = 12 V$ $U=12V$

Current is $I = 6 A$ $I=6A$

The power is

$P = U I = 12 \cdot 6 = 72 W$ $P=UI=12*6=72W$

Velocity is $v = \frac{4}{5} m s^{- 1}$ $v=4/5ms^-1$

Mass is $m = 2 k g$ $m=2kg$

The kinetic energy is

$K E = \frac{1}{2} m v^{2} = \frac{1}{2} \cdot 2 \cdot {(\frac{4}{5})}^{2} = \frac{16}{25} J$ $KE=1/2mv^2=1/2*2*(4/5)^2=16/25J$

But,

$E = P \cdot t$ $E=P*t$

The time is $t = \frac{E}{P} = \frac{\frac{16}{25}}{72} = 0.009 s$ $t=E/P=(16/25)/72=0.009s$

An electric toy car with a mass of 2kg2 kg is powered by a motor with a voltage of 12V12 V and a current supply of 6A6 A. How long will it take for the toy car to accelerate from rest to 45ms4/5 m/s?