An electric toy car with a mass of $1 k g$ $1 kg$ is powered by a motor with a voltage of $12 V$ $12 V$ and a current supply of $15 A$ $15 A$ . How long will it take for the toy car to accelerate from rest to $5 \frac{m}{s}$ $5 m/s$ ?

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Answer 1 · 2017-10-03T06:24:41

The time is $= 0.069 s$ $=0.069s$

The power is

$P = U I$ $P=UI$

The voltage is $U = 12 V$ $U=12V$

The current is $I = 15 A$ $I=15A$

The power is

$P = U I = 12 \cdot 15 = 180 W$ $P=UI=12*15=180W$

The kinetic energy of the car is

$E = \frac{1}{2} m v^{2}$ $E=1/2mv^2$

The mass is $m = 1 k g$ $m=1kg$

The speed is $v = 5 m s^{- 1}$ $v=5ms^-1$

so,

$E = \frac{1}{2} \cdot 1 \cdot {(5)}^{2} = 12.5 J$ $E=1/2*1*(5)^2=12.5J$

Let the time $= (t) s$ $=(t)s$

$E = P t$ $E=Pt$

$t = \frac{E}{P} = \frac{12.5}{180} = 0.069 s$ $t=E/P=(12.5)/180=0.069s$

An electric toy car with a mass of 1kg1 kg is powered by a motor with a voltage of 12V12 V and a current supply of 15A15 A. How long will it take for the toy car to accelerate from rest to 5ms5 m/s?