A small metal ball with a mass of 10 grams and a charge of 5.0 mC is located in a region of space with an electric field of 12 N/C directed to the east.The ball is released from rest at a distance of 30 cm above the ground.What is the speed of the ball just before it hits the ground?

Question

Quizplus · Accepted Answer

First, let's calculate the electric force acting on the ball:
F = qE
F = (5.0 × 10^-3 C)(12 N/C) = 0.06 N

Next, let's find the acceleration of the ball using Newton's second law:
F = ma
a = F/m
a = (0.06 N)/(0.01 kg) = 6 m/s^2

Now, let's find the distance the ball falls before hitting the ground:
d = 0.3 m

Finally, we can use the kinematic equation to find the final velocity:
v^2 = vi^2 + 2ad
vi = 0 m/s (since the ball is released from rest)
v^2 = 2(6 m/s^2)(0.3 m) = 3.6 m^2/s^2
v = √(3.6 m^2/s^2) = 1.9 m/s

Therefore, the best choice is D, 2.8 m/s (rounded to one significant figure).

A Small Metal Ball with a Mass of 10 Grams