Question 11
In a machine, many
couples act on a rotating object as shown.
What is the resultant
torque acting on the rotating object?
A 4.7 N m B 8.6
N m C 9.3
N m D 17.1
N m
Reference: Past Exam Paper – June 2017 Paper 12 Q11
Solution:
Answer:
C.
Torque of a couple = force
× perpendicular distance between the
2 forces
The torque may be
clockwise or anticlockwise.
Clockwise torque is due
to: 30 N force
Anticlockwise torque is
due to: 50 N, 16 N and 25 N forces
Clockwise torque = 30 × (6.5×2)
= 390 Ncm
Anticlockwise torque = (50×4.0×2)
+ (16×10×2) + (25×12×2) = 1320 Ncm
why did u multiply 2 in each torque for e,g 30*(6.5*2), Where did this 2 come from
ReplyDeletebecause of the couples. that is, each of the forces occur in pair
DeleteExplain in brief why multiplied by 2
ReplyDeletebecause the forces form a couple. so, we take the distance between the 2 forces. this is twice the distance from the centre
Deletewhy is 2 multiplied
ReplyDeletenot understand why we not direct multiply forces with distances.
ReplyDeleteas explained in the comment above,
Deletebecause the forces form a couple. so, we take the distance between the 2 forces. this is twice the distance from the centre
not understand why we not direct multiply forces with distances.
ReplyDeletethis can also be done but the workings would be too lengthy
Delete