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 $18 A$ $18 A$ . How long will it take for the toy car to accelerate from rest to $7 \frac{m}{s}$ $7 m/s$ ?

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Answer 1 · 2018-06-19T14:10:30

The time is $= 0.51 s$ $=0.51s$

The power is

$P = U I$ $P=UI$

$Power = Voltage \times Current$ $"Power"="Voltage"xx"Current"$

The voltage is $U = 8 V$ $U=8V$

The current is $I = 18 A$ $I=18A$

The power is

$P = U I = 8 \times 18 = 144 W$ $P=UI=8xx18=144W$

The kinetic energy of the car is

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

The mass of the car is $m = 3 k g$ $m=3kg$

The speed is $v = 7 m s^{- 1}$ $v=7ms^-1$

So,

The kinetic energy is

$E = \frac{1}{2} m v^{2} = \frac{1}{2} \times 3 \times {(7)}^{2} = 73.5 J$ $E=1/2mv^2=1/2xx3xx(7)^2=73.5J$

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

$E = P t$ $E=Pt$

$Energy=Power \times time$ $"Energy=Power" xx "time"$

The time is

$t = \frac{E}{P} = \frac{73.5}{144} = 0.51 s$ $t=E/P=(73.5)/144=0.51s$

An electric toy car with a mass of 3kg3 kg is powered by a motor with a voltage of 8V8 V and a current supply of 18A18 A. How long will it take for the toy car to accelerate from rest to 7ms7 m/s?