5.1.6 Resultant Forces

• What is a resultant force?

  The resultant force is the single force that represents the combined effect of all the individual forces acting on an object.
• How does the resultant force affect an object's motion?

  The resultant force determines whether an object will accelerate, decelerate, remain at rest, or move at a constant speed.
• How do you calculate the resultant force when forces act in the same direction?

  • Add their magnitudes together.
  • Resultant Force = F1 + F2 + ...
• How do you calculate the resultant force when forces act in opposite directions?

  • Subtract the smaller force from the larger force.
  • Resultant Force = Larger Force - Smaller Force
• What method is used to find the resultant force when forces are at an angle?

  • Use vector addition, often involving trigonometry.
  • For perpendicular forces, the Pythagorean theorem can be used.
• What does Newton's First Law state about resultant force?

  If the resultant force on an object is zero, the object will remain at rest or continue to move at a constant velocity.
• What does Newton's Second Law state regarding resultant force?

  If the resultant force is not zero, the object will accelerate in the direction of the resultant force.
• What is the formula to calculate acceleration using resultant force?


  F = m × a
• What does F represent in the formula F = m × a?

  F represents the resultant force in Newtons (N).
• What does m represent in the formula F = m × a?


  m represents the mass of the object in kilograms (kg).
• What does a represent in the formula F = m × a?

  a represents the acceleration in meters per second squared (m/s²).
• What is the resultant force when a car is pushed with a force of 200 N to the right and another force of 100 N to the right?

  • Resultant Force = 200 N + 100 N = 300 N to the right
• What is the resultant force when a box is pulled with a force of 150 N to the right and a force of 100 N to the left?

  • Resultant Force = 150 N - 100 N = 50 N to the right
• What is the resultant force when a book is resting on a table with a gravitational force of 10 N down and a normal force of 10 N up?

  • Resultant Force = 10 N down - 10 N up = 0 N
  • The book remains at rest.
• What are balanced forces?

  • Forces that cancel each other out (resultant force = 0).
  • The object remains stationary or continues moving at a constant velocity.
• What are unbalanced forces?

  • Forces that do not cancel each other out (resultant force ≠ 0).
  • The object will accelerate in the direction of the resultant force.
• What does it mean for an object to be in equilibrium?

  • The resultant force on it is zero.
  • The object stays at rest or moves at a constant speed in a straight line.
• What are some practical applications of understanding resultant forces?

  • Vehicle motion: Explains acceleration, deceleration, or steady speed.
  • Engineering: Important for designing structures to withstand forces.
  • Everyday life: Relevant in activities like pushing a shopping cart or playing sports.
• What is the summary of resultant force?

  • The resultant force is the overall force acting on an object after all individual forces are combined.
  • If the resultant force is zero, the object stays at rest or moves at a constant speed.
  • If the resultant force is not zero, the object will accelerate in the direction of the resultant force.