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 $7 A$ $7 A$ . 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 · 2017-06-22T05:56:43

The time is $= 0.15 s$ $=0.15s$

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

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

The power of the motor is

$P = U I = 12 \cdot 7 = 84 W$ $P=UI=12*7=84W$

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

Mass is $m = 1 k g$ $m=1kg$

The kinetic energy of the car is

$K E = \frac{1}{2} m v^{2} = \frac{1}{2} \cdot 1 \cdot {(5)}^{2} = 12.5 J$ $KE=1/2mv^2=1/2*1*(5)^2=12.5J$

But,

$E = P \cdot t$ $E=P*t$

The time is $t = \frac{12.5}{84} = 0.15 s$ $t=(12.5)/84=0.15s$

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 7A7 A. How long will it take for the toy car to accelerate from rest to 5ms5 m/s?