An electric toy car with a mass of $3 kg$ is powered by a motor with a voltage of $7 V$ and a current supply of $3 A$ . How long will it take for the toy car to accelerate from rest to $5/2 m/s$ ?

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Answer 1 · 2017-03-04T16:02:13

The time is $=0.45s$

Mass, $m=3kg$

Velocity, $v=5/2=2.5ms^-1$

Voltage, $V=7V$

Current, $I=3A$

Power, $P=IV=7*3=21W$

Energy, $E=1/2mv^2=1/2*3*2.5^2=9.375J$

Energy = Power x time

$E=Pt$

$t=E/P=9.375/21=0.45s$

An electric toy car with a mass of 3 kg3 kg is powered by a motor with a voltage of 7 V7 V and a current supply of 3 A3 A. How long will it take for the toy car to accelerate from rest to 5/2 m/s5/2 m/s?