Which piece of lab equipment would be least useful in finding the precise density of an unknown liquid?
a. beaker
b. graduated cylinder c. electronic balance
d. triple-beam balance

the answer is neither ball has a charge.

because if they were both positively charged, they will repel each other.

if they were positively and negatively charged, they will seek.

t = 1/400 h   ⇔ 0.0025 h ⇔ 9s ⇔ 0.15 m

any of the answers are correct.

answercollision;