Advertisements
Advertisements
Question
A uniform metre scale is balanced at a 40 cm mark when weights of 20 gf and 5 gf are suspended at 5 cm mark and 75 cm mark respectively. Calculate the weight of metre scale.
Advertisements
Solution
A metre scale is a uniform, therefore its weight acts at a 50 cm mark.
Taking moments about to cm mark.
A moment in the clockwise direction,
= W × 10 cm + 5 gf × 35 cm
= 10 W cm + 175 gf cm.
moment in anti-clockwise direction,
= 20 gf × 35 cm
= 700 gf cm.
By the law of moments,
Moments in clockwise direction = moments in anti-clockwise directions.
10 W cm + 175 gf cm = 700 gf cm
∴ 10 W cm = (700 − 175) gf cm
∴ W = `525/10` gf = 52.5 gf.
RELATED QUESTIONS
How does the magnitude of this non-contact force on the two bodies depend on the distance of separation between them?
What is the SI unit of the moment of force?
To obtain a given moment of force for turning a body, the force needed can be decreased by
What are non-contact forces? Give two example
State the relationship between force, mass and acceleration. Draw graphs showing the relationship between Acceleration and force for a constant mass.
The moment of a force of 10 N about a fixed point O is 5 N m. Calculate the distance of the point O from the line of action of the force.
A wheel of diameter 2 m is shown in the figure with the axle at O. A force F = 2 N is applied at B in the direction shown in the figure. Calculate the moment of force about
- the centre O, and
- the point A.
Calculate the resultant moment of forces about O and state its direction in fig.
Fig. 5 shows a uniform meter scale weighing 200 gf. Provided at its centre. Two weights 300 gf and 500 gf are suspended from the ruler as shown in the diagram. Calculate the resultant torque of the ruler and hence calculate the distance from mid-point where a 100 gf should be suspended to balance the meter scale.
State the units of moment of force.
