An electric toy car with a mass of $6 k g$ $6 kg$ is powered by a motor with a voltage of $5 V$ $5 V$ and a current supply of $7 A$ $7 A$ . How long will it take for the toy car to accelerate from rest to $\frac{8}{3} \frac{m}{s}$ $8/3 m/s$ ?

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Answer 1 · 2018-05-23T09:21:17

The time is =0.61s

The power is

$P = U I$ $P=UI$

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

The voltage is $U = 5 V$ $U=5V$

The current is $I = 7 A$ $I=7A$

The power is

$P = U I = 5 \cdot 7 = 35 W$ $P=UI=5*7=35W$

The kinetic energy of the car is

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

The mass of the car is $m = 6 k g$ $m=6kg$

The speed is $v = \frac{8}{3} m s^{- 1}$ $v=8/3ms^-1$

So,

The kinetic energy is

$E = \frac{1}{2} m v^{2} = \frac{1}{2} \cdot 6 \cdot {(\frac{8}{3})}^{2} = 21.33 J$ $E=1/2mv^2=1/2*6*(8/3)^2=21.33J$

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

$E = P t$ $E=Pt$

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

The time is

$t = \frac{E}{P} = \frac{21.33}{35} = 0.61 s$ $t=E/P=(21.33)/35=0.61s$

An electric toy car with a mass of 6kg6 kg is powered by a motor with a voltage of 5V5 V and a current supply of 7A7 A. How long will it take for the toy car to accelerate from rest to 83ms8/3 m/s?