Test: Force - SSC CGL MCQ

In physics, force is described as an external push or pull exerted on an object, which can change or attempt to change the state of rest or of uniform motion. It is measured in newton (N) in the SI unit and in dyne in the CGS unit. One newton is equivalent to 10^5 dyne. Understanding force is crucial as it is fundamental in explaining the motion and behavior of objects in the physical world.

When the sum of all forces acting on a body is zero, the body is said to be in equilibrium. This implies that the forces acting in different directions cancel each other out, resulting in a balanced state where the body remains either at rest or in a constant state of motion. Understanding equilibrium is essential in analyzing the stability of structures and predicting the behavior of objects under various forces.

The SI unit for force is newton (N), while the CGS unit for force is dyne. It's important to grasp the different units of measurement used in physics to accurately quantify and compare forces acting on objects in various contexts.

In circular motion, the force directed towards the center of the circular path is known as the centripetal force. This force is essential for keeping an object moving in a circular path by continuously pulling it towards the center. Without this force, objects would move in a straight line tangent to the circle. It is crucial in various phenomena such as planetary orbits, roller coaster rides, and swinging objects on a string.

In circular motion, the centrifugal force appears to act outwardly opposite to the centripetal force. However, it is not a real force but rather a pseudo or apparent force. It is a consequence of inertia, the tendency of objects to keep moving in a straight line. Centrifugal force is felt by objects in circular motion as they seem to be pushed away from the center, even though in reality, they are only following a straight path.

In circular motion, centripetal and centrifugal forces are equal in magnitude but act in opposite directions. The centripetal force pulls objects towards the center of the circle, while the centrifugal force appears to push them away from the center. This balance between the two forces allows an object to move in a circular path without flying off tangentially. Understanding this equilibrium is crucial in explaining the mechanics of circular motion in various real-world scenarios.

When a bucket of water is revolved rapidly in a vertical plane, the centrifugal force prevents the water from falling out, even when the bucket is inverted. Centrifugal force is an outward force that acts on objects moving in a curved path, pushing them away from the center of rotation. This force is responsible for the water remaining inside the bucket, defying gravity and the tendency of the water to spill out.

If a car exceeds the safe speed limit on a turn, the inner tires, experiencing a larger centrifugal force due to a smaller radius, may skid. This skidding occurs because the inner tires cannot maintain sufficient traction to counteract the force pushing them outward during the turn, resulting in a loss of control and potential skidding.

Torque is the product of force and the perpendicular distance from the axis of rotation. It produces a rotational effect, leading to angular acceleration in an object. When a force is applied at a distance from the axis of rotation, torque causes the object to rotate around that axis. This rotational effect is crucial in understanding how forces influence the motion of objects in rotational dynamics.

Among the four fundamental forces in nature, the strong nuclear force is considered the strongest. This force is responsible for holding protons and neutrons together within atomic nuclei. It is a short-range force that acts over distances comparable to the size of a nucleus. The strong nuclear force plays a crucial role in the stability of atomic nuclei and is essential for understanding nuclear physics and the structure of matter.

The gravitational force between the Earth and the Sun serves as the centripetal force for Earth's revolution around the Sun. This force is responsible for keeping the Earth in its elliptical orbit around the Sun. Gravity is a fundamental force of nature that governs the motion of celestial bodies in the solar system. The balance between the gravitational force pulling the Earth towards the Sun and the Earth's inertia moving it tangentially around the Sun results in the stable orbit we observe.

The four fundamental forces in nature—gravity, electromagnetism, the weak nuclear force, and the strong nuclear force—play a crucial role in shaping the interactions between all matter in the universe. Understanding these forces is fundamental in explaining various phenomena, from the behavior of subatomic particles to the dynamics of celestial bodies.

• Magnetic Force:
  • This is a non-contact force because it can act at a distance without needing the objects to touch each other.
  • For example, a magnet can pull a piece of iron toward it from afar.
• Frictional Force:
  • This is a contact force that happens when two surfaces come into contact and interact with each other.
• Impact Force:
  • This is also a contact force that occurs when two objects collide with each other.

The outward appearance of force in circular motion is attributed to the centrifugal force. This force seems to push objects away from the center of the circle, counteracting the centripetal force that pulls objects towards the center. The perception of this outward force is due to the inertia of the object, which resists changes in its direction of motion. While not a true force in itself, understanding centrifugal force is crucial in comprehending the dynamics of objects in circular motion.

• A device called a ball-bearing consists of two rings and two metal balls that can move freely.
• Its main purpose is to stop sliding and make a machine's parts roll over each other.
• By doing this, it changes static friction into rolling friction.