Question

Which one of the following statements is wrong?
A. Direction of torque is parallel to axis of rotation
B. Direction of moment of couple is perpendicular to the plane of rotation of body
C. Torques vector is perpendicular to both position vector and force vector
D. The direction of the force vector is always perpendicular to the directions of both position vector and torques vector.

Answer 1

Hint: To answer this question, we first need to understand what torque is. Torque is the rotational equivalent of linear force in physics and mechanics. Depending on the subject of study, it is also known as the moment, moment of force, rotating force, or turning effect. Archimedes' study of the use of levers gave birth to the notion.


Complete step-by-step solution:
Force - In physics, a force is any interaction that, while unopposed, causes an object to change its velocity. A force can cause a mass item to change its velocity (which includes starting to move from a standstill), i.e., accelerate. Intuitively, force can be described as a push or a pull. A force is a vector quantity since it has both magnitude and direction. The SI unit of Newton is used to measure it (N). The letter F is used to indicate force.
Moment - In physics, a moment is an expression that accounts for how a physical quantity is positioned or ordered by combining the product of a distance and a physical quantity. Moments are commonly defined in terms of a specific reference point, and they deal with physical values that are at a certain distance from that point. The product of a force on an item and the distance from the reference point to the object is the moment of force, also known as torque. A moment can be created by multiplying any physical quantity by a distance. Forces, masses, and electric charge distributions are all often used quantities.
So, we conclude that the force vector's direction is not necessarily perpendicular to both the position vector's directions. It can be at any angle to the vector of position. The torque is calculated using the perpendicular to r component of F.
So, the final answer is option (D) The direction of the force vector is always perpendicular to the directions of both position vector and torques vector.

Note:In physics, a vector is a quantity with both magnitude and direction. It's usually represented by an arrow with the same direction as the amount and a length proportionate to the magnitude of the quantity. A vector does not have position, even though it has magnitude and direction.