An electric toy car with a mass of 6 kg is powered by a motor with a voltage of 3 V and a current supply of 8 A. How long will it take for the toy car to accelerate from rest to 7/2 m/s?

1 Answer
Mar 20, 2016

1.53 "s"

Explanation:

The power input is the product of the voltage and the current.

P = IV

= (3 "V") * (8 "A")

= 24 "W"

The change in kinetic energy for the car is

Delta "KE" = 1/2 m (v^2 - v_0^2)

= 1/2 (6 "kg") ((7/2 "m/s")^2 - (0 "m/s")^2)

= 36.75 "J"

Thus, the time needed is the energy divided by the power.

t = frac{Delta "KE"}{P}

= frac{36.75 "J"}{24 "W"}

= 1.53 "s"