What is the density of lead (in g/cm3) if a rectangular bar measuring 0.50 cm in height, 1.55 cm in width, and 25.00 cm in length has a mass of 218.9 g ? express your answer using two significant figures?

Explanation:

density is defined as the measure of the mass of a matter per unit volume. it describes the sopace occupied by a substance relative to its volume.

Density = mass ÷ volume

ρ = m ÷ v

Volume = length × width × height

Volume of lead bar = l ×  w × h

V = 25 × 1.55 × 0.5

V = 19.375cm³

mass of bar = 218.9g

ρ = 218.9 ÷ 19.375

ρ = 11.2980g/cm³

ρ = 11g/cm³

electrical potential energy =0.072 j

explanation:

electrical potential energy is given by

u= q δv

q= charge=6 c

δv= potential difference and is given by

δv= e d

e= electric field

d= distance=5 mm=0.005 m

δv=2.4 (0.005)=0.012 v

now electric potential energy= u= q δv

u=6 (0.012)

u=0.072 j

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.