Most important numerical questions of all subjects of Civil Engineering

Question 1.

A force p of 50 N and another force Q of unknown magnitude act at 90° to each other. They are balanced by a force of 130 N. The magnitude of Q is

Previously Asked in : ||

60 N

80 N

100 N

120 N

Detailed Explanation :

Given that : P = 50N ; θ = 90° ; Resultant force (R) = 130N.

we known that ;

Resultant force (R) = √ (P² +Q² + 2PQcosθ)

Put the given value in above equation;

130 = √ 50² +Q² + 2 x 50 x Q x cos90°)

On Squaring both side; Also we know that cos90° = 0

⇒ 130² = 50² + Q²

⇒ 16900 = 2500 + Q²

⇒ Q² = 16900 – 2500

⇒ Q² = 14400

⇒ Q = √ (14400)

Q = 120 N

Hence 120 N option is correct