JAMB - Physics (1986 - No. 45)
A uniform meter rule QR is balanced on a knife edge which is 55cm from R, when a mass of 10g is hung at P as shown above, the mass of the meter rule is
550g
350g
70g
35g
説明
Taking a moment about the support.
m(55 - 50) = 10(90 - 55)
5 m = 10 x 35
5 m = 350
m = \(\frac{350}{5}\) = 70g