Question

A 0.246 kg toy car is powered by one D cell (1.50 V) connected directly to a small DC motor. The car has an effective energy conversion efficiency of 30.6 % , meaning that 30.6 % of the electric energy applied to the motor is converted into translational kinetic energy. After 7.88 s , the car, which is initially at rest, reaches a speed of 2.89 m / s . What is the average current supplied to the car's motor?

Answer 1

0.284 A

Step-by-step explanation:

We are given that

Mass,m=0.246 kg

Potential difference,V=1.50 V

Efficiency=30.6%

Time,t=7.88 s

Initial speed=0

Speed,v=2.89 m/s

Kinetic energy=
`K.E=(1)/(2)mv^2`

Using the formula

`K.E=(1)/(2)(0.246)(2.89)^2=1.027 J`

30.6% of Electric energy=K.E

`E=(K.E* 100)/(30.6)`

`E=(1.027* 100)/(30.6)=3.357 J`

`E=VIt`

`I=(E)/(Vt)=(3.357)/(1.5* 7.88)`

`I=0.284 A`