Physics Laws of Motion Quiz

Laws of Motion

• Change in Momentum: The change in momentum of a body is directly proportional to the force applied and the time for which it acts.
• Impulse: Impulse is defined as the product of force and time. It is also the change in momentum of a body.
  • S.I. unit of impulse is Newton × sec.

Newton's Laws of Motion

• Newton's First Law of Motion (Law of Inertia): An object at rest will stay at rest, and an object in motion will stay in motion with the same speed and in the same direction, unless acted upon by an unbalanced force.

• Newton's Second Law of Motion (Law of Acceleration): The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

• Newton's Third Law of Motion (Law of Action and Reaction): For every action, there is an equal and opposite reaction

Derivation of Law of Conservation of Linear Momentum

• Newton's third law states that for a force applied by an object A on object B, object B exerts back an equal force in magnitude, but opposite in direction.
• The total momentum of a system remains constant if no external forces act on the system.

Impulse

• The impulse imparted to a ball of mass 'm' striking a rigid wall with speed 'u' and rebounding back with the same speed is -2mu.

Friction

• Coefficient of Friction (μ): The coefficient of friction between two surfaces is the ratio of limiting frictional force to the normal force between them.
• Coefficient of Kinetic Friction (μs): The coefficient of kinetic friction between two surfaces is the ratio of force of kinetic friction to the normal force between them.

Forces Acting on a Block on an Inclined Surface

• Normal Force (N): The force acting perpendicular to the surface
• Gravitational Force (mg): The force acting vertically downward
• Frictional Force (f): The force opposing motion, acting parallel to the surface
• Component of Gravitational Force Parallel to the Inclined Plane (mg sin θ): The component of gravitational force acting down the inclined surface
• Component of Gravitational Force Perpendicular to the Inclined Plane (mg cos θ): The component of gravitational force acting perpendicular to the inclined surface

Newton's First Law of Motion and Inertia

• Inertia: Inertia is the tendency of an object to resist a change in its motion.
• Measure of Inertia: Mass is a measure of the inertia of a body.
• External Force and Direction of Motion: A body does not always move in the direction of the external force acting on it.
  • If multiple forces are acting, the net force will determine the direction of motion.
  • If the force is perpendicular to the direction of motion, the object will change direction without changing speed.