Moments, balance and structural design

9.In an experiment to find the centre of gravity of an irregular lamina, the lamina is suspended from a pin. It comes to rest with its centre of gravity:

10.A man uses a spanner to turn a nut. He applies a force of 40 N at a distance of 0.25 m from the pivot. What is the moment?

11.A beam is in equilibrium with three forces: F1 = 10 N at 0.2 m left of pivot (anticlockwise), F2 = 15 N at 0.3 m right of pivot (clockwise), and F3 at 0.1 m left of pivot (anticlockwise). What is the magnitude of F3?

12.A truck has a pivot near the front wheel. The load (weight) is 2.0 m from the pivot and the counterweight is 4.0 m from the pivot on the other side. If the counterweight is 5000 N, what is the maximum load that can be lifted without toppling?

13.A uniform metre rule is balanced horizontally on a pivot at its centre. A 4.0 N weight is placed 20 cm from the pivot on the left side. A 2.0 N weight is placed 30 cm from the pivot on the right side. What is the resultant moment about the pivot?

14.In an experiment to find the centre of gravity of an irregular lamina, the lamina is suspended from a pin through a hole near its edge. It comes to rest. Where is its centre of gravity relative to the point of suspension?

15.A student uses the suspension method to find the centre of gravity of an irregular plane lamina. After suspending the lamina from a hole and drawing the line of action of the weight, the student repeats the process with two more holes. The three lines intersect at a point. What does this point represent?

16.In the experiment to demonstrate equilibrium using a metre ruler and masses, which of the following is a control variable?

17.In the equilibrium experiment using a metre ruler, the ruler is balanced on a pin. One student suggests that friction between the ruler and the pin might affect the results. Which of the following is the best way to reduce this systematic error?

18.Which of the following is the correct definition of the centre of gravity of an object?

19.A uniform metre rule is balanced on a pivot at its centre. A 2.0 N weight is placed at the 20 cm mark on the left side. Where should a 3.0 N weight be placed on the right side to balance the rule?

20.A truck has a pivot near the front wheel. The load (weight) is 2.0 m from the pivot and the counterweight is 4.0 m from the pivot on the other side. The counterweight has a weight of 5000 N. What is the maximum load that can be lifted without the truck toppling?

21.Which of the following is a unit of moment?

22.In the experiment to find the centre of gravity of an irregular lamina, why is it important to punch the holes before drawing the lines?

23.An object will topple over when its centre of gravity:

24.The centre of gravity of an object is defined as:

25.A uniform metre rule is balanced at its centre. Where is its centre of gravity?

26.A force of 5 N is applied at a perpendicular distance of 20 cm from a pivot. What is the moment in N m?

27.Which of the following describes a system in equilibrium?

28.A uniform beam is balanced on a pivot. A 10 N weight is placed 0.4 m to the left of the pivot. Where must a 5 N weight be placed on the right to balance the beam?

29.An object is more stable when its centre of gravity is:

30.In an experiment to find the centre of gravity of an irregular lamina, the lamina is suspended from a hole near its edge. It comes to rest. Where is its centre of gravity?

31.A student uses the suspension method to find the centre of gravity of an irregular plane lamina. After suspending the lamina from a hole and drawing the line of action, what should the student do next?

32.A beam is acted upon by three forces: F1 = 10 N at 0.2 m left of pivot (anticlockwise), F2 = 15 N at 0.3 m right of pivot (clockwise), and F3 at 0.1 m left of pivot (anticlockwise). The beam is in equilibrium. What is the magnitude of F3?

33.A truck has a pivot near the front wheel. The load (weight) is 2.0 m from the pivot and the counterweight is 4.0 m from the pivot on the other side. The counterweight is 5000 N. The truck is in equilibrium. What is the load?

34.In the experiment to find the centre of gravity of an irregular lamina, the lamina is suspended from a pin through a hole near its edge. It comes to rest. Where is its centre of gravity located?

35.A truck has a pivot near the front wheel. The load (weight) is 2.0 m from the pivot and the counterweight is 4.0 m from the pivot on the other side. The counterweight is 5000 N. What is the maximum load that can be lifted without the truck toppling?

36.In an experiment to demonstrate equilibrium, a metre ruler is balanced on a pivot at its centre. A 100 g mass is hung at the 20 cm mark on the left, and a 200 g mass is hung at the 70 cm mark on the right. What is the resultant moment about the pivot? (Take g = 10 N/kg)

37.A student uses the suspension method to find the centre of gravity of an irregular plane lamina. After suspending the lamina from a hole and drawing the line of action of the weight, the process is repeated from two other holes. Why are three lines drawn?

38.A uniform beam of weight 120 N and length 6.0 m is supported at its ends. A load of 80 N is placed 2.0 m from the left end. What is the upward force at the left support?

39.Balance a ruler on a pivot using small known masses placed at different perpendicular distances. What is the independent variable?

40.Balance a ruler on a pivot using small known masses placed at different perpendicular distances. Which observation or quantity is the dependent variable?

41.Balance a ruler on a pivot using small known masses placed at different perpendicular distances. Which decision best controls another factor in this comparison?

42.Balance a ruler on a pivot using small known masses placed at different perpendicular distances. Why should the class repeat measurements or check multiple comparable observations?

43.A class is evaluating an application of moments, balance and structural design. Which statement identifies a relevant limitation?

44.Balance a ruler on a pivot using small known masses placed at different perpendicular distances. Which conclusion is most justified by a controlled comparison?

45.Balance a ruler on a pivot using small known masses placed at different perpendicular distances. Select the two practices that strengthen the validity of this comparison.

46.When evaluating evidence about moments, balance and structural design, select the two scientifically defensible statements.

47.Design a fair investigation for this question: Balance a ruler on a pivot using small known masses placed at different perpendicular distances. Identify what to compare, what to record and one control.

48.Explain one use of the science in moments, balance and structural design and evaluate one limitation of the evidence or application.

49.A 6.0 N force acts 0.40 m from a pivot. What opposing force at a perpendicular distance of 0.30 m balances its moment?

50.Clockwise and anticlockwise moments balance, but the resultant vertical force is non-zero. Is the object in full equilibrium?