1.
The moment of a force causes an object to
Correct Answer
D. Rotate about a specific point.
Explanation
The moment of a force refers to the turning effect it has on an object. When a force acts on an object, it can cause the object to rotate or turn about a fixed point. This means that the object will change its direction of motion without necessarily moving forward, moving backward, or stopping completely. Therefore, the correct answer is "turn about a fixed point."
2.
The turning effect of a force on a door is greater when it is applied at
Correct Answer
C. A point far away from the hinges and perpendicular to the door
Explanation
When a force is applied at a point far away from the hinges and perpendicular to the door, it creates a larger turning effect. This is because the perpendicular force creates a moment arm, which is the shortest distance between the point of application and the axis of rotation (hinges). The longer the moment arm, the greater the turning effect. Therefore, applying a force far away from the hinges and perpendicular to the door maximizes the turning effect.
3.
Two equal and oppositely directed forces acting on an object will be in equilibrium
Correct Answer
D. when their moments about the same point are equal
Explanation
When two equal and oppositely directed forces act on an object, they will be in equilibrium when their moments about the same point are equal. This means that the forces will not cause the object to rotate or move in any direction. The moments of the forces are determined by multiplying the magnitude of each force by its perpendicular distance from the point of rotation. If the moments of the forces are equal, then the object will remain balanced and in equilibrium.
4.
The diagram shows a light beam pivoted at one end. What is the effort required to lift the load?
Correct Answer
A. 50 N
Explanation
The diagram shows a light beam pivoted at one end. The effort required to lift the load can be determined by the length of the lever arm. In this case, the lever arm is longer on the side of the load compared to the side of the effort. Therefore, a smaller effort is required to lift the load. Among the given options, the only value that represents a smaller effort is 50 N.
5.
Jack has a weight of 300 N and sits 2.0 m from the pivot of the see-saw. Jill has a weight of 450 N and sits 1.5 m from the pivot. Who will move down?
Correct Answer
B. Jill
Explanation
Jill will move down because she has a greater weight than Jack and is sitting closer to the pivot. The see-saw will balance when the moments on both sides of the pivot are equal. The moment is calculated by multiplying the weight by the distance from the pivot. Since Jill has a greater weight and a shorter distance from the pivot, her moment will be greater, causing her side of the see-saw to move down.
6.
A nut can be loosen more easily with
Correct Answer
D. long spanner because a large turning effect can be produced.
Explanation
A long spanner can produce a larger turning effect because it has a longer lever arm. The lever arm is the distance between the point where the force is applied (in this case, the handle of the spanner) and the point where the force is exerted (the nut). By having a longer lever arm, the force applied to the nut is multiplied, resulting in a larger turning effect. Therefore, a long spanner is more effective in loosening a nut compared to a short spanner or a heavy spanner.
7.
The diagram shows a gauge which measures the amount of liquid in a tank. At which position should the pivot be placed so that the pointer moves the greatest distance as the tank is emptied?
Correct Answer
D. D
Explanation
The pivot should be placed at position D so that the pointer moves the greatest distance as the tank is emptied. This is because position D is the farthest point from the tank, allowing the pointer to have a larger range of motion as the liquid level decreases.
8.
Which of the following statements accurately describes the turning effect of forces?
Correct Answer
A. Torque is the force applied to an object to cause it to rotate around an axis.
Explanation
Torque, also known as the moment of force, is the measure of the turning effect of a force applied to an object. It is defined as the product of the force and the perpendicular distance from the axis of rotation to the line of action of the force.
9.
A uniform metre rule of weight 16.0 N is pivoted at the 60 cm mark. A 4.0 N weight is suspended from one end.
At the instant when the rule is horizontal, what is the value of the resultant turning moment about the pivot?
Correct Answer
A. Zero
Explanation
When the rule is horizontal, the weight of the metre rule and the weight suspended from one end create equal and opposite clockwise and anticlockwise moments respectively. Since these moments are equal in magnitude and opposite in direction, they cancel each other out, resulting in a net turning moment of zero about the pivot.
10.
Two types of moment of force are
Correct Answer
D. Clockwise and anti-clockwise
Explanation
The correct answer is "clockwise and anti-clockwise." This is because the moment of force, also known as torque, refers to the rotational force applied to an object. Clockwise and anti-clockwise are the two opposite directions in which torque can be applied, causing the object to rotate either in a clockwise or anti-clockwise direction.