Resultant Forces | Force & Motion | Physics | FuseSchool

FuseSchool - Global Education
16 Feb 202005:01
EducationalLearning
32 Likes 10 Comments

TLDRThis video script introduces the concept of forces as pushes or pulls on objects, emphasizing their vector nature with magnitude and direction. It explains how to use free body and vector diagrams to represent and calculate forces, including resultant forces from multiple forces acting on an object. Examples illustrate the application of these concepts, such as a car with opposing forces and a parachutist at terminal velocity. The script also demonstrates how to create scale diagrams to find the resultant force, using a parallelogram method and a given scale.

Takeaways
  • 📚 Forces are pushes or pulls that act on objects and can be named, such as normal contact force, tension, friction, air resistance, magnetic force, electrostatic force, and gravitational force.
  • 📝 Forces are vector quantities, having both magnitude and direction, unlike scalar quantities which only have magnitude.
  • 🔍 When multiple forces act on an object, they can be replaced by a single resultant force that has the same effect.
  • 🚗 The resultant force is calculated by subtracting the smaller force from the larger force, as demonstrated with the car example.
  • 🪂 A parachutist falling at terminal velocity experiences balanced forces, with gravity pulling down and air resistance pushing up equally.
  • 📊 Free body diagrams represent the forces acting on an object, with the object shown as a point and forces as arrows indicating magnitude and direction.
  • ✈️ In a free body diagram for an airplane, the forces of lift and weight must be equal for constant altitude, and thrust and drag must be equal for constant velocity.
  • 📐 Vector or scale diagrams show the forces acting on an object and the angle between them, which can be used to calculate the resultant force.
  • 📏 To draw a scale diagram, follow steps: draw arrows at correct angles, make a parallelogram, and measure the diagonal for the resultant force.
  • 🏃‍♀️ An example of using a scale diagram is calculating the resultant force on a runner being pushed by the wind at an angle.
  • 📈 The magnitude of the resultant force can be determined using a scale, such as 1 centimeter equals one newton in the runner example.
Q & A

  • What is a force according to the video script?

    -A force is a push or a pull that acts on an object.

  • How many types of forces are mentioned in the script?

    -Seven types of forces are mentioned: normal contact force, tension, friction, air resistance, magnetic force, electrostatic force, and gravitational force.

  • What are vector quantities?

    -Vector quantities are those that have both magnitude and direction, and can be represented by an arrow.

  • What is the definition of a resultant force?

    -The resultant force is a single force that can replace several forces acting on an object and has the same effect.

  • How is the resultant force calculated when two forces act in opposite directions?

    -The resultant force is calculated by subtracting the smaller force from the larger force.

  • What is terminal velocity and why does it occur?

    -Terminal velocity is the constant velocity at which a parachutist falls through the air due to the balance between the force of gravity and air resistance.

  • What is a free body diagram and how is it used?

    -A free body diagram is a representation of the forces acting on an object without showing the object itself. It is used to visualize and analyze the forces acting on an object.

  • What are the two forces acting on an airplane traveling at a constant velocity and altitude?

    -The two forces are lift (upwards) and weight (downwards), which must be equal in magnitude for the airplane to maintain a constant altitude.

  • How are scale or vector diagrams used to calculate the resultant force?

    -Scale or vector diagrams show the forces acting on an object and the angle between them. They are used to calculate the resultant force by drawing a parallelogram and measuring the diagonal.

  • What is the process for drawing a scale diagram to find the resultant force?

    -The process involves drawing arrows at the correct angles to represent the forces, drawing lines to form a parallelogram, and measuring the diagonal to find the magnitude of the resultant force.

  • What is the example given in the script to illustrate the use of a scale diagram?

    -The example involves a person running with a force of 10 newtons against a wind force of 8 newtons at a 30-degree angle, resulting in a resultant force of 17 newtons.

Outlines
00:00
📚 Introduction to Forces and Free Body Diagrams

This paragraph introduces the concept of force as a push or pull on an object and lists various types of forces. It explains that forces are vectors with both magnitude and direction, and can be represented by arrows. The concept of resultant force is introduced, which is the single force that replaces multiple forces acting on an object with the same effect. An example is given with a car pushed by two opposing forces, demonstrating how to calculate the resultant force. The paragraph also touches on the concept of balanced forces, using a parachutist at terminal velocity as an example, where the force of gravity is balanced by air resistance. Free body diagrams are introduced as a way to visually represent the forces acting on an object without showing the object itself.

🚁 Forces in Equilibrium and Vector Diagrams

This paragraph delves into the concept of equilibrium, where forces balance each other out, preventing acceleration. Using the example of a parachutist in free fall at terminal velocity, it illustrates how the downward force of gravity is counteracted by the upward force of air resistance. The paragraph then introduces free body diagrams, which depict the forces acting on an object as arrows emanating from a point, with the arrow's length representing force magnitude and direction. It continues with an example of an airplane in horizontal flight, where the forces of lift and weight, as well as thrust and drag, are balanced, maintaining constant velocity and altitude. The use of vector diagrams to represent and calculate the resultant force is also discussed, with a step-by-step guide on how to draw and interpret them.

🏃‍♀️ Calculating Resultant Forces with Vector Diagrams

This final paragraph focuses on the practical application of vector diagrams to calculate the resultant force acting on an object when multiple forces are present. It provides a step-by-step method for drawing and analyzing vector diagrams, including determining the correct angles for the forces, drawing a parallelogram to represent the forces, and measuring the diagonal to find the resultant force. An example scenario is given where a person is running against the wind, and the forces of running and wind resistance are combined to find the overall force experienced by the runner. The paragraph concludes with a brief mention of the importance of choosing sensible units for the diagram and encourages viewers to like, subscribe, and comment if they have questions, also suggesting the use of the 'few school app' for further learning.

Mindmap
Keywords
💡Force
A force is defined as a push or pull that acts upon an object, causing it to change its state of motion. In the video, force is central to the theme as it discusses how different forces act on objects like a car and a parachutist, and how they can be calculated using diagrams.
💡Vector Quantities
Vector quantities are physical quantities that have both magnitude and direction, unlike scalar quantities that only have magnitude. The video emphasizes that forces are vector quantities, which is crucial for understanding how they can be represented graphically and calculated using vector addition.
💡Resultant Force
The resultant force is the single force that can replace several forces acting on an object, having the same overall effect. The video illustrates this concept by showing how to calculate the resultant force acting on a car with opposing forces.
💡Terminal Velocity
Terminal velocity is the constant velocity that a freely falling object eventually reaches when the resistance of the medium through which it is falling prevents further acceleration. The video uses the parachutist as an example to explain how terminal velocity occurs when the force of gravity is balanced by air resistance.
💡Free Body Diagram
A free body diagram is a graphical representation of all the forces acting on an object, with the object represented as a point and the forces as arrows. The video demonstrates how to use free body diagrams to visualize and understand the forces acting on a parachutist and an airplane.
💡Magnitude
The magnitude of a force refers to its strength or size. The video explains how the magnitude of forces is depicted by the length of the arrows in diagrams and is essential for calculating resultant forces.
💡Direction
Direction is a critical aspect of vector quantities, including forces. The video shows how direction is indicated in diagrams by the orientation of the arrows representing forces and is necessary for understanding the effect of forces on objects.
💡Balanced Forces
Balanced forces occur when the forces acting on an object are equal in magnitude and opposite in direction, resulting in no net force and thus no change in the object's motion. The video uses the parachutist example to illustrate balanced forces at terminal velocity.
💡Lift
Lift is the upward force that opposes the weight of an object and is generated by the aerodynamic shape of a body moving through a fluid, like air. In the video, lift is discussed in the context of an airplane maintaining a constant altitude, where lift balances the weight of the plane.
💡Drag
Drag is the force that opposes the motion of an object through a fluid, such as air. The video explains how drag is a force that must be balanced by thrust for an airplane to maintain a constant velocity.
💡Thrust
Thrust is the force that propels an object forward, often generated by engines in vehicles like airplanes. The video mentions thrust in the context of an airplane, where it must be equal to the drag force for the plane to maintain a constant velocity.
💡Scale or Vector Diagrams
Scale or vector diagrams are graphical representations used to calculate the resultant force when multiple forces are acting at different angles. The video provides a step-by-step process for using scale diagrams to find the resultant force acting on a runner.
Highlights

A force is a push or a pull that acts on an object.

Forces can be named: normal contact force, tension, friction, air resistance, magnetic force, electrostatic force, and gravitational force.

Forces are vector quantities because they have both magnitude and direction, and so can be represented by an arrow.

Scalar quantities have only magnitude and no direction.

When several forces act on an object, they can be replaced by a single force that has the same effect, called the resultant force.

Example of calculating resultant force: A car with 10 newtons pushing it backwards and 30 newtons driving it forwards results in a 20 newtons forward force.

A parachutist falling at terminal velocity experiences balanced forces: 800 newtons downwards (gravity) and 800 newtons upwards (air resistance).

Free body diagrams represent forces acting on an object without showing the object itself.

In a free body diagram, the object is shown as a point, and forces are drawn as arrows starting at the point.

The length of the arrow in a free body diagram indicates the magnitude of the force, and the direction of the arrow shows the direction of the force.

Example of a free body diagram: An aeroplane traveling at a constant velocity and altitude has balanced lift and weight forces, and balanced thrust and drag forces.

Scale or vector diagrams show forces acting on an object and the angle between them, and can be used to calculate the resultant force.

Steps to draw scale diagrams: Draw arrows at correct angles, make a parallelogram, measure the diagonal for the resultant force.

Example of using a scale diagram: A person running with 10 newtons force and wind pushing with 8 newtons at 30 degrees results in a 17 newtons resultant force.

Conclusion: Free body and vector diagrams are useful tools to describe and calculate forces.

Transcripts

Browse More Related Video

Resultant vector | Vector addition: Grade 10 Physics

How to find Resultant Force - Two Forces Mechanics : ExamSolutions

GCSE Physics - Resultant Forces & Free Body Diagrams #42

Vector Sum of Forces

What is a Force & Types of Forces in Physics? - Gravity, Normal Force, Contact Forces - [1-5-1]

AP Physics B Kinematics Presentation General Problems #07

Rate This

5.0 / 5 (0 votes)

Thanks for rating:

Related Tags
Physics EducationForces ExplainedFree Body DiagramsVector DiagramsResultant ForceTerminal VelocityParachutist ForcesAerodynamicsMagnetic ForcesEducational VideoPhysics Concepts