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

Question

1384 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2018-01-02T13:45:59

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 $U = 7 V$ $U=7V$

The current is $I = 3 A$ $I=3A$

The power is

$P = U I = 7 \cdot 3 = 21 W$ $P=UI=7*3=21W$

The kinetic energy of the car is

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

The mass is $m = 3 k g$ $m=3kg$

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

so,

$E = \frac{1}{2} \cdot 3 \cdot {(\frac{8}{3})}^{2} = \frac{32}{3} J$ $E=1/2*3*(8/3)^2=32/3J$

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

$E = P t$ $E=Pt$

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

The time is

$t = \frac{E}{P} = \frac{\frac{32}{3}}{21} = 0.51 s$ $t=E/P=(32/3)/21=0.51s$

An electric toy car with a mass of 3kg3 kg is powered by a motor with a voltage of 7V7 V and a current supply of 3A3 A. How long will it take for the toy car to accelerate from rest to 83ms8/3 m/s?