P2.9 Newtons 1st and 2nd laws

• Newton's first law:

  A __________ force is required to change the motion of an object.

  resultant
• 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 no resultant force acts on it?

  It remains stationary
• What happens to a moving object if no resultant force acts on it?

  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
• What does non-zero mean in the context of forces?

  Anything other than zero
• 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 does acceleration affect an object moving to the left when a rightward force is applied?

  It can slow down or stop the object
• What is acceleration defined as?

  Change in velocity divided by change in time
• A moving object that has no resultant force acting upon it will:

  Continue moving at the same velocity
• Why does the moon accelerate even though its speed is constant?

  Its direction is constantly changing
• What causes the moon to orbit the Earth?

  The Earth's gravitational pull
• How is the size of the resultant force related to acceleration?

  It is directly proportional to acceleration
• What is the equation that relates force, mass, and acceleration?

  F = m a
• 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 for motion to remain unchanged
• How does an object's inertial mass relate to changing its velocity?

  It measures how difficult it is to change velocity
• How do you calculate inertial mass?

  By dividing force by acceleration
• What does a large mass indicate about inertia?

  It requires a large force to change velocity
• What is the relationship between force and acceleration in Newton's second law?

  Force equals mass times acceleration
• What happens to acceleration if the resultant force is doubled?

  It also doubles
• 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 force
  • Moving right: Speeds up
  • Moving left: Slows down or stops
  • Change in direction: Velocity changes without speed change
• How does circular motion relate to acceleration?

  • Constant speed but changing direction
  • Acceleration occurs due to direction change
  • Example: Moon's orbit around Earth
• What is the relationship between mass, force, and acceleration?

  • F = m a
  • Larger mass requires larger force for same acceleration
  • Inertial mass measures resistance to velocity change
• Which of the following could not be caused by a resultant force acting on an object?

  The object maintains constant velocity
• If an object changes direction (as the moon does as it orbits the earth), then its velocity will change as well (as velocity considers both speed and direction). As the objects velocity is changing, this means that it must be accelerating (as acceleration is just a change in velocity). 
• The formula for Newton's second law is:

  F=ma