Question

Larger the moment arm, greater will be the:
(A) Torque
(B) Velocity
(C ) Moment
(D) Axis of rotation

Answer 1

Hint: The moment and torque are two directly proportional quantities. Hence when the torque is large the moment also will be larger. The moment arm is actually a length. Thus torque can be defined as the cross product of this moment arm and force. Hence when one of these quantities increases the torque also increases. Hence here larger the moment arm indicates the larger value of torque itself.

Formula used:
$Torque=Force\times MomentArm$
$\tau =r\times F$
where, $\tau $ is the torque
r is the moment arm
F is the force

Complete step-by-step answer:
The moment arm is actually a length. Thus torque can be defined as the cross product of this moment arm and force. Hence when one of these quantities increases the torque also increases. Hence here larger the moment arm indicates the larger value of torque itself.
Then the torque at the axis is,
$Torque=Force\times MomentArm$
$\tau =r\times F$
where, $\tau $ is the torque
r is the moment arm
F is the force
We already said that the moment arm is a length. Hence it is a length between the axis of the joint and the line on which the force acts. The torque is otherwise known as the rotational force or moment of force. The maximum value of the moment arm is when the external force is at 90 degrees. This moment arm can also be defined as an influence of a force to produce a rotation around its axis. It will try to resist the force acting along it. Also the moment arm changes according to the changes with the angle on the application of the force. It is otherwise known as lever arm since it is the perpendicular distance between line of force and centre of moments.

So, the correct answer is “Option A”.

Note: Torque can never have a negative value. Because just like a force it can never have a negative value. That is, it is always a positive value. Like torque, negative force and energy never exist. The moment arm is actually a length. Thus torque can be defined as the cross product of this moment arm and force. Hence when one of these quantity increases the torque also increases. Hence here larger the moment arm indicates the larger value of torque itself.