An electric toy car with a mass of $15 k g$ $15 kg$ is powered by a motor with a voltage of $8 V$ $8 V$ and a current supply of $7 A$ $7 A$ . How long will it take for the toy car to accelerate from rest to $9 \frac{m}{s}$ $9 m/s$ ?

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Answer 1 · 2017-09-23T14:51:25

The time is $= 10.85 s$ $=10.85s$

The power is

$P = U I$ $P=UI$

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

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

The power is

$P = U I = 8 \cdot 7 = 56 W$ $P=UI=8*7=56W$

The kinetic energy of the car is

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

The mass is $m = 15 k g$ $m=15kg$

The speed is $v = 9 m s^{- 1}$ $v=9ms^-1$

so,

$E = \frac{1}{2} \cdot 15 \cdot {(9)}^{2} = 607.5 J$ $E=1/2*15*(9)^2=607.5J$

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

$E = P t$ $E=Pt$

$t = \frac{E}{P} = \frac{607.5}{56} = 10.85 s$ $t=E/P=(607.5)/56=10.85s$

An electric toy car with a mass of 15kg15 kg is powered by a motor with a voltage of 8V8 V and a current supply of 7A7 A. How long will it take for the toy car to accelerate from rest to 9ms9 m/s?