An electric toy car with a mass of #5 kg# is powered by a motor with a voltage of #1 V# and a current supply of #6 A#. How long will it take for the toy car to accelerate from rest to #4/5 m/s#?
It will take only 0.27 s to reach this speed.
This problem will be solved using energy considerations, demonstrating the ease with which energy connects different situations - electrical and mechanical.
Given the current and voltage supplied to the motor, we can calculate the power output:
This means that work is being done on the car at a rate of 6 joules per second.
For the rest of the problem, we will continue to work in energy terms.
The kinetic energy of the car, must change from zero to
Since work is being done at 6 J/s, the time required will be: