An electric toy car with a mass of $3 k g$ $3 kg$ is powered by a motor with a voltage of $4 V$ $4 V$ and a current supply of $7 A$ $7 A$ . How long will it take for the toy car to accelerate from rest to $4 \frac{m}{s}$ $4 m/s$ ?

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An electric toy car with a mass of $3 k g$ $3 kg$ is powered by a motor with a voltage of $4 V$ $4 V$ and a current supply of $7 A$ $7 A$ . How long will it take for the toy car to accelerate from rest to $4 \frac{m}{s}$ $4 m/s$ ?

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Answer 1 · 2017-06-07T18:19:48

I got $0.86 s$ $0.86s$

Explanation:

In reaching $4 \frac{m}{s}$ $4m/s$ the car will have a Kinetic Energy of:
$K = \frac{1}{2} m v^{2} = \frac{1}{2} \cdot 3 \cdot 4^{2} = 24 J$ $K=1/2mv^2=1/2*3*4^2=24J$

The Power deliverd by the motor is:

$P = V I = 4 \cdot 7 = 28 W$ $P=VI=4*7=28W$ that means that it delivers $28 J$ $28J$ each second.

The toy car will need $24 J$ $24J$ so using a proportion we get:

$1 sec : 28 J = x sec : 24 J$ $1"sec":28J=x"sec":24J$

or

$x = \frac{24}{28} = 0.857 \approx 0.86 s$ $x=24/28=0.857~~0.86s$

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An electric toy car with a mass of $3 k g$ $3 kg$ is powered by a motor with a voltage of $4 V$ $4 V$ and a current supply of $7 A$ $7 A$ . How long will it take for the toy car to accelerate from rest to $4 \frac{m}{s}$ $4 m/s$ ?

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Explanation:

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An electric toy car with a mass of 3kg3 kg is powered by a motor with a voltage of 4V4 V and a current supply of 7A7 A. How long will it take for the toy car to accelerate from rest to 4ms4 m/s?

1 Answer

Explanation:

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An electric toy car with a mass of $3 k g$ $3 kg$ is powered by a motor with a voltage of $4 V$ $4 V$ and a current supply of $7 A$ $7 A$ . How long will it take for the toy car to accelerate from rest to $4 \frac{m}{s}$ $4 m/s$ ?