Question

A uniform metal bar 100cm long balances at 20cm mark when a mass of 1.5kg is attached at 0cm mark calculate the weight of the bar (Take g=10N/kg)

Answer 1

Answer:

30 N

Explanation:

there are two forces act on the bar:

- weight of 1.5 kg mass, w = mg = 15 N

- weight of the bar, wb

for balance,

w * Lw = wb * Lwb

Lw = length of bar from the mass to the pivot

Lwb = lenght of bar from the center of the bar to the pivot

15 * 20 = wb * (50-20)

300 = wb * 30

wb = 300/30 = 30 N