Embedded Files
Objectives:
Objectives:
Help students explain the concepts of force, net force, and balanced/unbalanced forces.
Enable students to solve problems using F=m×a and calculate net force.
Teach students to draw and analyze free-body diagrams to connect visual understanding with calculations.
What is force?
What is force?
A force is a push or pull that can cause an object to move, stop, or change its motion. Forces can be either balanced (no change in motion) or unbalanced (causing motion changes).
Real-life Examples:
Real-life Examples:
A person pushing a box.
When a person pushes a box, several forces are at work:
Applied Force: The person uses their strength to push the box forward. The harder they push, the faster the box can move.
Friction: The ground pushes back against the box, making it harder to move. If the box is heavy or the surface is rough, the friction is stronger.
Motion: Once the person pushes hard enough to overcome friction, the box starts to move. If they stop pushing, the box slows down and stops because of friction.
This example shows how force is needed to move something, and how the ground can slow things down!
Types of Forces
Types of Forces
Contact Force is a type of force that occurs when two objects are in physical contact with each other.
Frictional Force
Frictional force opposes the relative motion or tendency of motion between two surfaces in contact. It depends on the nature of the surfaces and the normal force acting between them.
Example: The force that slows down a sliding rock on a rough floor.
Normal Force
Normal force is the support force exerted by a surface perpendicular to the object resting on it. It counteracts the force due to gravity acting on the object.
Example: The upward force a table exerts on a book placed on it.
Tension Force
Tension force is the pulling force transmitted through a string, rope, cable, or chain when it is stretched. It acts along the length of the material.
Example: The force in a rope holding up a hanging box.
Applied Force
Applied Force
Applied force is the external force exerted on an object by a person or another object to move it or change its state of motion.
Example: Pulling the handle of Lat Pulldown machine at the gym.
Air Resistance Force
Air resistance force is a type of frictional force that opposes the motion of objects moving through the air. It depends on the object's speed, shape, and surface area.
Example: The force slowing down a falling parachute.
Buoyant Force
Buoyant force is the upward force exerted by a fluid on an object submerged or partially submerged in it, counteracting gravity.
Example: The force that allows a boat to float on water.
Spring/Restoring Force
Spring force is the force exerted by a compressed or stretched spring, trying to return to its equilibrium position. It follows Hooke's law, proportional to the displacement.
Example: The force pulling back a stretched spring.
Non-contact Force is a type of force that acts on an object without any physical contact between the objects involved.
Gravitational Force
Gravitational force is the attractive force that acts between two objects with mass, pulling them toward each other. It is responsible for phenomena like objects falling to the ground and the orbits of planets.
Example: The force that keeps the Moon in orbit around Earth.
Electromagnetic Force
Electromagnetic force is the force between charged particles, which can be attractive or repulsive, and is responsible for electric and magnetic phenomena. It governs interactions like the behavior of magnets and the flow of electric currents.
Example: The force that makes a magnet attract another magnet.
Net Force
Net Force
The net force is defined as the vector sum of all the forces acting on an object. It plays a crucial role in determining the object's motion, as described by Newton's second law of motion, which states that the net force acting on an object is equal to the mass of the object multiplied by its acceleration (Fnet=m⋅a)
The net force is the total force resulting from all individual forces acting on an object, taking into account both their magnitudes and directions. If multiple forces act in different directions, they can be combined to find a single resultant force, which is the net force.
Balanced Force
Balanced Force
No net force; objects stay stationary or move at constant speed.
Unbalanced Force
Unbalanced Force
Nonzero net force; objects accelerate in the direction of the net force.
Example: Equal tug of war.
Example: Equal tug of war.
Here's how it works:
Each team pulls with an equal amount of force in opposite directions.
The rope stays in place in the center because the forces on both sides are equal and opposite.
In this scenario, since the forces cancel each other out, the rope doesn't move in either direction, and there is no change in position. This is an example of balanced forces, where both sides are exerting the same force, resulting in no movement.
Example: A group of people pushing the car.
Example: A group of people pushing the car.
Here how it's works:
When the people push hard enough to overcome the friction, the forces become unbalanced.
The pushing force applied by the group of people is greater than the resisting friction and the inertia of the car.
This results in an unbalanced force, which causes the car to accelerate and move in the direction they are pushing.
Let's have a fun games about force!
Let's have a fun games about force!
Just click which game are you playing
Free Body Diagram
Free Body Diagram
In many situations, an object is affected by multiple forces, such as gravity, friction, normal, and applied forces. A Free Body Diagram (FBD) visually represents these forces and, when placed on a Cartesian plane, breaks them into X- axis and Y-axis components. This makes it easier to analyze the net forces and predict the object’s motion. FBDs are crucial for understanding and solving problems involving forces in two dimensions.
ANSWER
When a man pushes a box, several forces act on it, which can be analyzed on a Cartesian plane. The applied force pushes the box forward, while the frictional force opposes the motion along the horizontal (X-axis). Vertically (Y-axis), the gravitational force pulls the box downward, while the normal force pushes upward, balancing the weight of the box. Together, these forces determine the box’s motion and equilibrium, with the net force calculated by isolating the horizontal and vertical components.
Watch the video about free diagrams
Checking For Understanding
Checking For Understanding
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