Solved MCQs | Chapter 3 Dynamics | Physics 9th | Balochistan Textbook Board Quetta | Urdu\Hindi

1. Encircle the correct option. The number of rectangular components of force are: (a) 2 (b) 3 (c) 4 (d) 5 A force of 10N makes and angle of 30° with x-axis. Its vertical or y-component will be: (a) 4N (b) 5N (c) 8.7N (d) 10N A force of 10N makes and angle of 60° with the x-axis. Its horizontal or x-component will be: (a) 4N (b) 5N (c) 8.7N (d) 10N If F_x and F_y are horizontal and vertical components of a force, then magnitude of the force is given by: (a) F_x+F_y (b) F_x^2+F_y^2 (c) √(F_x^2+F_y^2 ) (d) √(F_x+F_y ) The formula for the direction of the force from its rectangular components is: (a) 〖sin〗^(-1) (F_y/F_x ) (b) 〖cos〗^(-1) (F_y/F_x ) (c) 〖tan〗^(-1) (F_y/F_x ) (d) 〖sin〗^(-1) (F_x/F_y ) The SI unit of torque is (a) Nm (b) Nm^(-1) (c) Ns (d) Ns^(-1) The perpendicular distance between the axis of rotation of a body and the line of action of force applied on it is called: (a) torque (b) moment arm (c) tension (d) momentum The anticlockwise torque is taken as (a) positive (b) negative (c) zero (d) none of those The first condition of equilibrium is represented by: (a) ∑▒〖F_x=0〗 (b) ∑▒〖F_y=0〗 (c) ∑▒〖F_x=0〗 & ∑▒〖F_y=0〗 (d) ∑▒〖τ=0〗 The second condition of equilibrium is represented by: (a) ∑▒〖F_x=0〗 (b) ∑▒〖F_y=0〗 (c) ∑▒〖τ=0〗  (d) ∑▒〖F_x=0〗 & ∑▒〖F_y=0〗 The centre of gravity of an irregularly shaped plane lamina can be determined by: (a) metre rod (b) wedge (c) inclined plane (d) plumb line