A balanced lever has two weights on it, the first with mass 5 kg 5kg and the second with mass 35 kg35kg. If the first weight is 9 m9m from the fulcrum, how far is the second weight from the fulcrum?

1 Answer
Dec 12, 2016

= 1.29m (3s.f.) =1.29m(3s.f.)

Explanation:

use turning moments:

M_1 * D_1 = M_2 * D_2M1D1=M2D2

(MM being mass of weight on lever, DD being distance from fulcrum)

M_1 = 5kgM1=5kg
M_2 = 35kgM2=35kg

D_1 = 9mD1=9m

find D_2D2:

M_1 * D_1 = 5 * 9 = 45M1D1=59=45
M_2 * D_2 = 35 * D_2 = 45M2D2=35D2=45

D_2 = (45/35) mD2=(4535)m

= (9/7)m=(97)m

= 1.29m (3s.f.) =1.29m(3s.f.)