# Class 9 Physics Chapter 4 Important Short Questions 2024

Students if you are looking for the 9th Class Physics Chapter 4 Turning Effect of Forces Short Questions Notes if yes? then you visit the right place where you can easily find Physics Chapter No. 4 most important short questions without answers but it is your responsibility to find answers from your 9th class Physics book.

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## 9th Class Physics Chapter 4 Short Questions Notes

• Parallel forces have their lines of action parallel to each other.
• If the direction of parallel forces is the same, they are called parallel forces. If two parallel forces are in opposite directions to each other, then they are called unlike parallel forces.
• The sum of two or more forces is called the resultant force.
• A graphical method used to find the resultant of two or more forces is called head to tail rule.
• Splitting up a force into two components perpendicular to each other is called the resolution of that force.
• A force can be determined from its perpendicular components.
• The torque or moment of a force is the turning effect of the force. The torque of a force is equal to the product of force and the moment arm of the force.
• According to the principle of moments, a body in equilibrium is equal to the sum of anticlockwise moments acting on it.
• The Centre of mass of a body is such a point where a net force causes it to move without rotation.
• The center of gravity of a body is a point where the whole weight of a body acts vertically downward.
• A couple is formed by two parallel forces of the same magnitude but acting in opposite directions along different lines of action.
• A body is in equilibrium if the net force acting on it is zero. A body in equilibrium either remains at rest or moves with a uniform velocity.
• A body is said to satisfy the second condition for equilibrium if the resultant torque acting on it is zero.
• A body is said to be in stable equilibrium if, after a slight tilt, it returns to its previous position.
• If a body does not return to its previous position when set free after a slight tilt is said to be in unstable equilibrium.