P10

• What are Newton's first and second laws of motion about?

  They describe motion and forces acting on objects
• What does Newton's first law state about resultant force?

  A resultant force is needed to change motion
• What happens to a stationary object if the resultant force is zero?

  The object will remain stationary
• What occurs if a moving object's resultant force is zero?

  It continues moving at the same velocity
• What does Newton's second law state about non-zero resultant force?

  It causes an object to accelerate
• If a particle has unbalanced forces acting on it, what direction will it accelerate?

  In the direction of the resultant force
• What can happen to an object when it accelerates to the right?

  It can start moving, speed up, or slow down
• How is acceleration defined in terms of velocity and time?

  Change in velocity divided by change in time
• Why does the moon accelerate even with constant speed in circular motion?

  Its direction is constantly changing
• How does the size of the resultant force relate to acceleration?

  It is directly proportional to acceleration
• If a particle has a mass of 0.25 kg and experiences a resultant force of 12 N, what is its acceleration?

  $48 \text{ m/s}^2$
• What is inertia?

  The tendency of an object to maintain motion
• How does an object's inertial mass relate to changing its velocity?

  It measures difficulty in changing velocity
• How do you calculate inertial mass?

  By dividing force by acceleration
• What does a large mass indicate about an object's inertia?

  It requires a large force to change velocity
• What are the key concepts of Newton's first and second laws of motion?

  • First Law: Resultant force needed to change motion
  • Second Law: Non-zero resultant force causes acceleration
  • Inertia: Tendency to maintain current motion
• What are the effects of acceleration on an object based on its initial motion?

  • Stationary: Starts moving in the direction of acceleration
  • Moving right: Speeds up
  • Moving left: Slows down or stops
  • Change in direction: Velocity changes without speed change
• What is the relationship between force, mass, and acceleration?

  • Resultant force is proportional to acceleration
  • Equation: $F =$$m \cdot a$
  • Inertial mass measures resistance to acceleration
• What is gravity defined as?

  A force of attraction between two objects
• What factors determine the size of the gravitational force?

  The mass of the objects and their distance
• Why is the gravitational force negligible for small objects like apples?

  Because they have relatively low masses
• How does distance affect gravitational force for large objects?

  Greater distance reduces the gravitational force
• What is the gravitational field around an object called?

  Gravitational field
• What is the gravitational field strength on Earth?

  Approximately 9.8 newtons per kilo
• What is the gravitational field strength on the Moon?

  Approximately 1.6 newtons per kilo
• What does an object experience when it enters a gravitational field?

  A force of attraction
• How do you calculate an object's weight?

  Mass times gravitational field strength
• What is required to lift an object against gravity?

  Energy or work
• What is the formula for gravitational potential energy?

  ep = mgh
• What units are used for gravitational potential energy?

  Joules
• How do you convert 100 grams to kilos?

  Divide by 1000
• What is the gravitational potential energy of a 100-gram apple thrown 3 meters up?

  2.94 joules
• What are the key takeaways about gravity, weight, and gravitational potential energy?

  • Gravity is a force of attraction.
  • Weight = mass × gravitational field strength (9.8 N/kg on Earth).
  • Gravitational potential energy (ep) = mass × gravitational field strength × height.
• What is terminal velocity?

  It's when velocity remains constant during free fall.
• What happens to an object at terminal velocity?

  It no longer accelerates or decelerates.
• What force acts on a person stepping out of an airplane?

  Gravity pulls them downwards as weight.
• What is the force called that pulls a person downwards?

  Weight
• How does the weight of a person change during free fall?

  The magnitude of their weight remains constant.
• What happens to the resultant force when a person first steps out of the plane?

  The resultant force equals the weight since it's the only force.
• What force opposes the weight of a falling person?

  Air resistance acts upwards against weight.