Question

2) Playing with your younger sibling's toy car (m- 32g), you notice that if you launch it with an initial velocity of 1.5m/s along the ground, it takes 6ft before the car comes to a stop due to rolling friction and drag. You want to see if you can make it stop faster without touching it, so you apply a uniform electric field of magnitude 9,100N/C pointing to the left to the area in which you're testing the car, and you charge the car. You send the car to the right with the same velocity and this time, it stops in 2.9ft. How much charge is on the car, and what is the sign of the charge (positive or negative)?

Answer 1

Since force of electric field qE on the car acts in the same direction of field(i.e. towards left)so we can say that sign of charge is positive.