Newton's Laws Quiz

Newton's Laws

• Resultant forces cause acceleration, calculated using Newton's laws of motion. Weight is a gravitational effect.
• Newton's first law states that an object's motion remains unchanged unless a resultant force acts upon it. If the resultant force is zero:
  • A stationary object stays stationary.
  • A moving object continues moving at the same velocity.
• Examples of uniform motion (constant velocity):
  • A car traveling at a constant speed, where driving force equals resistive forces (air resistance and friction).
  • A runner at top speed with thrust equaling air resistance.
  • An object at terminal velocity with air resistance equaling weight.
• Balanced forces result in zero resultant force and no acceleration. Objects remain at rest or move at constant velocity.

Newton's Second Law

• Newton's second law describes force, mass, and acceleration using the equation: Resultant force = mass × acceleration (F = ma).
• Force is measured in newtons (N).
• Mass is measured in kilograms (kg).
• Acceleration is measured in meters per second squared (m/s²).
• Acceleration is directly proportional to the resultant force and inversely proportional to the mass. An increase in force or a decrease in mass leads to an increase in acceleration.

Examples of Non-Uniform Motion

• Newton's first law explains non-uniform motion where speed changes or direction changes.
• A car accelerating has driving force greater than resistive forces, resulting in non-zero resultant force.

Forces on a Submarine

• A submarine experiences both vertical and horizontal forces.
• Balanced horizontal forces result in zero horizontal acceleration.
• Balanced vertical forces result in zero resultant vertical acceleration.
• The submarine continues in its current state (stationary or constant velocity) without any external direction change.

Newton's Third Law

• Newton's third law states that whenever two objects interact, they exert equal and opposite forces on each other.
• Examples:
  • A person pushing a pram, where person's push on pram and pram push back on person.
  • Car tyre on a road, where tyre pushes road and road pushes tyre.
  • Satellite in Earth orbit, where Earth pulls satellite and satellite pulls Earth.

Weight, Mass, and Gravitational Field Strength

• Weight is the force of gravity acting on an object. It's calculated as weight (W) = mass (m) × gravitational field strength (g).

• Mass is a measure of the amount of matter in an object (measured in kilograms, kg).

• Gravitational field strength is measured in newtons per kilogram (N/kg).

• Weight is directly proportional to mass, meaning more mass means more weight; the gravitational field strength is constant.

• Measuring weight involves measuring the force needed to balance the object's weight. This is typically done using a spring balance which measures the force required to counter the weight.