Class 6 Force MCQ with Answers

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Attempt Class 6 Force MCQs covering types of forces, contact, non-contact, friction, and gravity.
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Quick Revision: Force

  • Force: A push or a pull that can change the state, speed, direction, or shape of a body. It has both magnitude and direction (vector quantity).
  • Effects of Force: (1) Move a stationary body, (2) Stop a moving body, (3) Change speed, (4) Change direction of motion, (5) Change shape/size. Force does not change mass.
  • SI Unit: Newton (N). Gravitational unit: kilogram-force (kgf). 1 kgf ≈ 10 N.
  • Spring Balance: Measures weight (force). Works on the principle that the increase in spring length is directly proportional to the weight suspended.
  • Contact Forces: Forces that require actual contact between bodies. Examples: Muscular force (push/pull by muscles), Force of tension (in a string/wire), Force of reaction (acts normal to the surface).
  • Non-Contact Forces: Forces that act from a distance without physical contact. Examples: Gravitational force (always attractive — Earth pulls objects down), Magnetic force (attract/repel — unlike poles attract, like poles repel), Electrostatic force (charged objects attract/repel).
  • Weight vs Mass: Weight is the force with which Earth attracts a body (SI unit: N). Mass is the quantity of matter (SI unit: kg). Force changes weight but not mass.
  • Friction: The force that opposes relative motion between two surfaces in contact. Always acts opposite to the direction of motion.
  • Cause of Friction: Interlocking of irregular projections (hills and valleys) on the surfaces in contact.
  • Static Friction: Maximum opposing force while the body is stationary. It is self-adjusting — increases with applied force up to a limit.
  • Sliding Friction: Opposing force when a body slides over a surface. Less than static friction.
  • Rolling Friction: Opposing force when a body rolls over a surface. The least of the three types.
  • Order of Friction: Static > Sliding > Rolling (for the same mass).
  • Factors Affecting Friction: Depends on the nature of surfaces (rough = more friction, smooth = less) and weight of the body (heavier = more friction). Does not depend on the area of surfaces in contact.
  • Methods to Reduce Friction: Polishing, Lubrication (oil/grease), Ball bearings (convert sliding to rolling friction), Streamlining (pointed shape to reduce fluid friction).
  • Methods to Increase Friction: Making surfaces rough (sprinkling sand on icy roads), using brake pads, treads on tires.
  • Advantages of Friction: Walking (reaction of friction moves us forward), Writing, Braking, Holding objects, Lighting a matchstick.
  • Disadvantages of Friction: Causes wear and tear of moving parts, produces unwanted heat (reduces efficiency), requires more energy to overcome.
  • Fluid Friction: Friction experienced by bodies moving through liquids or gases. Least in gases, more in liquids, most between solids. Streamlining reduces fluid friction (e.g., sharp arrows, fish shape).
  • Balanced vs Unbalanced Forces: Balanced forces are equal and opposite, resulting in zero net force (no change in motion). Unbalanced forces cause a change in the state of motion.
  • Non-Contact Force & Distance: Magnitude of non-contact forces (gravitational, magnetic, electrostatic) depends on the distance between bodies. If distance doubles, force becomes one-fourth.

Force Class 6 Questions and Answers (FAQ)

What is force and what are its effects in Class 6 Science?
Force is a push or a pull that can change the state of motion, speed, direction, or shape of a body. Its main effects are: moving a stationary body, stopping a moving body, changing speed, changing direction of motion, and changing shape or size. Force does not change the mass of a body. The SI unit of force is the Newton (N).
What is the difference between contact force and non-contact force?
Contact forces require actual physical contact between two bodies. Examples include muscular force, force of tension, force of reaction, and friction. Non-contact forces act from a distance without any physical contact. Examples include gravitational force, magnetic force, and electrostatic force. The magnitude of non-contact forces depends on the distance between the bodies.
What is friction and what are its three types?
Friction is the force that opposes relative motion between two surfaces in contact. It arises due to interlocking of surface irregularities. The three types are: static friction (when a body is stationary, it is the highest), sliding friction (when a body slides over a surface), and rolling friction (when a body rolls over a surface, it is the lowest). The order is: Static > Sliding > Rolling.
How can we reduce friction and why is it important?
Friction can be reduced by: polishing surfaces, using lubricants like oil and grease, using ball bearings (which convert sliding friction to rolling friction), and streamlining the shape of objects moving through fluids. Reducing friction is important because it decreases wear and tear of machine parts, reduces unwanted heat production, and improves the efficiency of machines.
What is the difference between mass and weight for Class 6 students?
Mass is the quantity of matter in a body and is measured in kilograms (kg). It remains constant everywhere. Weight is the force with which the Earth attracts a body towards its center and is measured in Newtons (N). Weight can change if the gravitational force changes, but a force has no effect on the mass of a body. The weight of a body of mass 1 kg is approximately 10 N on Earth.

Chapter Summary: Force

Force is defined as a push or a pull that can change the state of motion, speed, direction, or shape of a body. It is a vector quantity with both magnitude and direction. The SI unit of force is the Newton (N). Forces are broadly classified as contact forces (muscular force, force of tension, force of reaction, friction) which require physical contact, and non-contact forces (gravitational, magnetic, electrostatic) which act from a distance. Weight is the force with which Earth attracts a body, while mass is the quantity of matter — force can change weight but not mass.

Friction is the force that opposes relative motion between two surfaces. It arises due to interlocking of surface irregularities. Static friction is the highest, followed by sliding friction, with rolling friction being the least. Friction depends on the nature of surfaces and the weight of the body, but not on the area of contact. It can be reduced by polishing, lubrication, ball bearings, and streamlining. Friction is both advantageous (walking, writing, braking, holding) and disadvantageous (wear and tear, heat production). The magnitude of non-contact forces varies with distance — doubling the distance reduces the force to one-fourth. Balanced forces produce no change in motion, while unbalanced forces cause a change in the state of motion.

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