ICSE Class 10

General instructions: Answer all questions. Marks are shown in brackets [ ].

Objective

1. 1.
   The moment of a force about a given axis depends

   1. A. only on the magnitude of force
   2. B. only on the perpendicular distance of force from the axis
   3. C. neither on the force nor on the perpendicular distance of force from the axis
   4. D. both, on the force and its perpendicular distance from the axis
   [1]
2. 2.
   What is meant by the equilibrium of a body?

   1. A. A body is in equilibrium when it is at rest or moving with constant velocity and not rotating.
   2. B. A body is in equilibrium when only the resultant force acting on it is zero, regardless of rotation.
   3. C. A body is in equilibrium when it is accelerating linearly but not rotating.
   4. D. A body is in equilibrium when the forces acting on it are balanced but moments may cause rotation.
   [1]
3. 3.
   Which of the following correctly defines the term 'centre of gravity of a body'?

   1. A. The point where the mass of the body is equally distributed in all directions.
   2. B. The point at which the entire weight of the body can be considered to act.
   3. C. The geometric centre of the body, regardless of its weight distribution.
   4. D. The point where the body experiences the maximum gravitational force.
   [1]
4. 4.
   Where is the centre of gravity of a uniform ring situated?

   1. A. At the centre of the ring.
   2. B. At the edge of the ring.
   3. C. Midway between the centre and the edge.
   4. D. Outside the ring, along its axis.
   [1]
5. 5.
   State one way to reduce the moment of a given force about a given axis of rotation.

   1. A. Increase the magnitude of the force applied.
   2. B. Reduce the perpendicular distance from the axis of rotation to the line of action of the force.
   3. C. Change the direction of the force to be parallel to the axis of rotation.
   4. D. Apply the force at a point farther from the axis of rotation.
   [1]
6. 6.
   The turning effect of a force depends on which of the following factors?

   1. A. The magnitude of the force and the angle at which it is applied
   2. B. The magnitude of the force and the perpendicular distance from the axis of rotation
   3. C. The mass of the object and the speed of the applied force
   4. D. The direction of the force and the surface area of the object
   [1]
7. 7.
   Which of the following correctly describes the position of the centre of gravity in unstable equilibrium?

   1. A. The centre of gravity is at its highest position (e.g., a cone on its apex).
   2. B. The centre of gravity is at its lowest position (e.g., a cone on its base).
   3. C. The centre of gravity remains at the same height (e.g., a rolling ball).
   4. D. The centre of gravity is at the midpoint of the object's height.
   [1]
8. 8.
   A fulcrum divides a crowbar in the ratio 3:1. What weight will be lifted if an effort of 100 N is applied at the end of its longer arm?

   1. A. 100 N
   2. B. 200 N
   3. C. 300 N
   4. D. 400 N
   [1]
9. 9.
   The centrifugal force is

   1. A. a real force
   2. B. the force of reaction of centripetal force
   3. C. a fictitious force
   4. D. directed towards the centre of circular path
   [1]
10. 10.
    A wheel is pivoted at its centre (O) as shown in the diagram . A force of 20 N is applied tangentially at a point on its rim, 0.3 m from the centre. Which labelled part or value correctly represents the moment of force produced?

    1. A. 6 N m (the product of 20 N and 0.3 m)
    2. B. 20 N (the applied force alone)
    3. C. 0.3 m (the radius of the wheel)
    4. D. 6.67 N m (20 N divided by 3 m)
    [1]
11. 11.
    Define moment of couple and identify its S.I. unit.

    1. A. The product of one force and the perpendicular distance between the forces; S.I. unit is newton-metre (Nm).
    2. B. The sum of two forces acting in opposite directions; S.I. unit is newton (N).
    3. C. The product of mass and acceleration; S.I. unit is kilogram-metre per second squared (kgm/s²).
    4. D. The perpendicular distance between two forces; S.I. unit is metre (m).
    [1]
12. 12.
    When does a body rotate? Which of the following is one way to change the direction of rotation of the body, along with a suitable example?

    1. A. A body rotates when an unbalanced force acts on it. Reverse the force direction; e.g., pushing a door handle left instead of right.
    2. B. A body rotates when an unbalanced moment acts on it. Reverse the direction of the applied force; e.g., turning a door handle clockwise instead of anticlockwise.
    3. C. A body rotates when its center of mass shifts. Increase the force magnitude; e.g., pushing a door harder to make it swing faster.
    4. D. A body rotates when friction is eliminated. Change the pivot point; e.g., moving the hinge of a door to the opposite side.
    [1]
13. 13.
    Assuming the centre of gravity of a uniform rod is at its midpoint, how is the position of the centre of gravity of a triangular lamina determined?

    1. A. It lies at the intersection of the medians of the triangle.
    2. B. It lies at the midpoint of the longest side of the triangle.
    3. C. It lies at the point where the altitudes of the triangle meet.
    4. D. It lies at the average of the vertices' coordinates.
    [1]
14. 14.
    A mechanic can open a nut by applying a force of 150 N while using a lever handle of length 40 cm. What length of handle, in metres, is required if he wants to open the same nut by applying a force of only 50 N?

    1. A. 0.4 m
    2. B. 1.2 m
    3. C. 3.0 m
    4. D. 0.133 m
    [1]
15. 15.
    Why does skidding usually occur on a rainy day along a curved path?

    1. A. The road becomes smoother, increasing friction.
    2. B. The force of friction decreases, failing to provide necessary centripetal force.
    3. C. The vehicle's tires become more adhesive to the road.
    4. D. The centripetal force required becomes zero on a rainy day.
    [1]
16. 16.
    Why is it easier to carry two buckets (one in each hand) rather than one bucket in one hand?

    1. A. Two buckets balance the load, keeping the centre of gravity low and stable.
    2. B. One bucket is heavier than two buckets combined.
    3. C. Two buckets reduce the total weight due to distribution.
    4. D. One bucket shifts the centre of gravity, making it harder to walk straight.
    [1]
17. 17.
    An effort of 50 kgf is applied at the end of a lever of the second order, which supports a load of 750 kgf, such that the load is at a distance of 0.1 m from the hinge. Find the length of the lever. (Assume that the lever is weightless)

    1. A. 0.1 m
    2. B. 1.5 m
    3. C. 0.2 m
    4. D. 0.8 m
    [1]
18. 18.
    Prove that the moment of a couple is equal to the product of one of the forces and the couple arm. Which of the following correctly explains this relationship?

    1. A. A couple consists of two equal and opposite forces separated by a perpendicular distance, and their moments add up to Force × couple arm.
    2. B. The moment of a couple is the difference between the moments of the two forces, resulting in Force × couple arm.
    3. C. A couple's moment is calculated by multiplying the sum of the two forces by the couple arm.
    4. D. The moment of a couple is independent of the distance between the forces and equals the magnitude of one force.
    [1]
19. 19.
    Given the figure shows a heavy roller with axle at O to be pulled onto pavement XY, in which direction should the minimum possible force be applied?

    1. A. Parallel to the pavement XY.
    2. B. Perpendicular to the radius at the point of contact.
    3. C. Along the line joining O and the point of contact.
    4. D. At a 45-degree angle to the pavement.
    [1]
20. 20.
    Why are racing cars designed to be very broad and very low in height?

    1. A. To increase the centre of gravity for better aerodynamics
    2. B. To keep the centre of gravity very low, ensuring stability during sharp turns at high speeds
    3. C. To reduce the weight of the car for higher speeds
    4. D. To allow for larger fuel tanks and more power
    [1]