5.7 Newton's Law of Motion

• What does Newton's First Law of Motion state?

  Objects remain at rest or constant velocity
• What happens if the resultant force on an object is zero?

  The object remains stationary or moves uniformly
• What does it mean for an object to move with constant velocity?

  It moves at the same speed and direction
• How can Newton's First Law explain uniform velocity?

  Balanced forces result in zero resultant force
• What is required for constant velocity to be achieved?

  Forces on the object must be balanced
• Why is velocity considered a vector quantity?

  It has both speed and direction
• What does Newton's Second Law of Motion state?

  Acceleration is proportional to resultant force
• How does mass affect acceleration according to Newton's Second Law?

  Greater mass results in smaller acceleration
• What is the equation for Newton's Second Law?

  F = ma
• What do the variables in the equation F = ma represent?

  F = force, m = mass, a = acceleration

  
• How do you calculate acceleration from velocity and time?

  a = Δv / t

  
• What is the acceleration of a car that goes from 0 to 27 m/s in 3 seconds?

  9 m/s²
• What force is required to accelerate a 900 kg car at 9 m/s²?

  8100 N
• How does Newton's Second Law apply to different masses?

  Same force causes different accelerations
• What happens to acceleration if mass increases while force remains constant?

  Acceleration decreases
• What is the approximate mass of an adult person?

  ~70 kg
• How do you estimate acceleration during a collision?

  Calculate change in velocity over time

  
• What is the estimated deceleration of a car that stops from 20 m/s in 0.1 seconds?

  ~−200 m/s²
• How do you calculate the force on a passenger during a collision?

  F = ma
• What is the estimated force on a passenger with mass 70 kg and deceleration −200 m/s²?

  ~−14,000 N
• What are the key variables in investigating force and acceleration?

  • Independent variable: Force (F)
  • Dependent variable: Acceleration (a)
  • Control variable: Mass (m)
• What is the aim of the experiment investigating the effect of varying force on acceleration?

  • To investigate how varying force affects acceleration
  • Object mass remains constant
• What is the aim of the experiment investigating the effect of varying mass on acceleration?

  • To investigate how varying mass affects acceleration
  • Force remains constant
• What is the method for measuring acceleration in the experiments?

  1. Measure intervals on the bench
  2. Use a pulley system with weights
  3. Record time for each interval
  4. Calculate average speed and acceleration
• How do you analyze results from the experiments on force and acceleration?

  • Determine average speed between intervals
  • Calculate acceleration for different weights
  • Compare acceleration results
• What is the aim of the experiment investigating mass on acceleration?

  To investigate the effect of varying mass
• What is the independent variable in the experiment?

  Mass, m
• What is the dependent variable in the experiment?

  Acceleration, a
• What are the control variables in the experiment?

  • Force, F
• How should the string be positioned in the experiment?

  It should be horizontal and parallel to the bench
• What should be done to ensure the car accelerates gently?

  Select a weight that provides constant force
• What should you do when releasing the car?

  Release it simultaneously with starting the stopwatch
• How can you calculate average speed in the experiment?

  Use distance and average time for intervals
• What equation is used to calculate acceleration?

  Acceleration = change in speed / time

  
• What is a systematic error in the experiment?

  Not transferring weights to maintain constant mass
• What is a random error in the experiment?

  Measurement inaccuracies in timing intervals
• What safety consideration should be taken during the experiment?

  Don't stand under the weight hanger
• What is Newton's third law of motion?

  • Forces between two bodies are equal and opposite
  • Forces arise in pairs

  
• How does Newton's third law explain walking?

  The foot pushes ground back, ground pushes foot forward
• What does a free body force diagram illustrate?

  The forces acting on an object