A uniform beam PQ of length 80 cm and weight 60 N rests on a support at X where | PX | = 30 cm. If the body is kept in equilibrium by a mass m kg which is placed at P , calculate the value of m
[Take g = 10 ms\(^{-2}\)]
A.
2.0
B.
3.0
C.
2.5
D.
4.0
Correct answer is C
∑ clock wise moments =∑ anti clock wise moments
= 60 x 10 = 30 x m
= 600 = 30 m
m = \(\frac{600}{30} = 20 N\)
W = mg ==> m = \(\frac{W}{g}\)
∴ m = \(\frac{20}{10} = 2kg\)