Newton’s Laws

• What is the gravitational field strength on the Moon?

  $1.6 \text{ N/kg}$
• How does the mass of the Moon compare to that of the Earth?

  The Moon has a smaller mass than the Earth
• If a 1 kg mass is on the Moon, what is its weight?

  $1.6 \text{ N}$
• What is the weight of a 5 kg mass on the Moon?

  $8 \text{ N}$
• What is the mass of a person who weighs 120 N on the Moon?

  $75 \text{ kg}$
• What is the weight of the same person on Earth where $g =$$10 \text{ N/kg}$?


  $750 \text{ N}$
• What does inertia refer to in physics?

  A reluctance to move or change motion
• How does the mass of an object affect its inertia?

  More mass means more inertia
• What is needed to change the motion of an object with high inertia?

  A greater resultant force
• Why is a full bucket of sand more difficult to push than an empty bucket?

  Because it has more mass and therefore more inertia
• What are Newton's three laws of motion?

  1. An object at rest stays at rest, and an object in motion stays in motion unless acted upon by a force.
  2. The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
  3. For every action, there is an equal and opposite reaction.
• What is the difference between mass and weight?

  • Mass: The amount of matter in an object, measured in kilograms (kg).
  • Weight: The force exerted by gravity on that mass, measured in newtons (N).
• What are the implications of inertia in everyday life?

  • Objects resist changes in their state of motion.
  • Greater mass requires more force to change motion.
  • Understanding inertia helps in vehicle safety and design.
• Who created the three laws of motion?

  Isaac Newton
• What do Newton's laws of motion describe?

  The relationship between a body and the forces acting upon it
• What is mass?

  • The amount of matter in an object
  • Measured in kilograms (kg) or grams (g)
• How is weight defined?

  Weight is the force of gravity on your mass
• What is the unit of weight?

  Newtons (N)
• What does the gravitational field strength represent?

  The force of attraction between all objects
• How does mass affect the force of gravity?

  The more mass an object has, the larger the force of gravity it exerts
• What is the gravitational field strength on Earth?

  10 N/kg
• What is the weight of a 1 kg mass on Earth?

  10 N
• What is the weight of a 5 kg mass on Earth?

  50 N
• How can you find weight, mass, or gravitational field strength using the Wmg triangle?

  • Use the formula: \(W = m \times g\)
  • Rearrange to find any variable
• How do you calculate the weight of a person with a mass of 65 kg on Earth?

  W = m × g = 65 kg × 10 N/kg = 650 N
• When do you become weightless?

  When gravitational field strength reduces to 0 N/kg
• What happens to gravitational field strength as you travel away from Earth?

  It reduces
• What are the key concepts related to mass and weight?

  • Mass is the amount of matter in an object
  • Weight is the force of gravity on that mass
  • Weight is calculated using the formula \(W = m \times g\)
  • Gravitational field strength on Earth is 10 N/kg
• The Wmg triangle can be used to find weight (W), or mass (m) or gravitational field strength (g).
• What do Newton's laws of motion describe?

  The relationship between a body and the forces acting upon it
• What is Newton's First Law of Motion?

  A body will continue in its state of rest or uniform motion unless acted upon by a net force
• What does it mean for forces to be balanced?

  It means the resultant force is zero
• If an object is at rest, what can be said about the forces acting on it?

  The forces acting on it are balanced
• What happens to an object moving at constant velocity when balanced forces act on it?

  It continues to move at constant velocity
• What is the definition of resultant force?

  The single force that could replace all the forces acting on an object
• What does it mean for an object to hover or float in terms of forces?

  It means the forces acting on it are balanced
• How does the thrust and drag relate to the motion of a car according to Newton's First Law?

  If thrust equals drag, the car travels at constant speed
• What is the effect of balanced forces on an object that is still?

  The object remains still
• What is the effect of balanced forces on a floating boat?

  The boat remains floating
• What are the key concepts of Newton's First Law of Motion?

  • A body remains at rest or in uniform motion
  • Balanced forces result in no change in motion
  • Net force must act to change the state of motion