Knowing the Scientific Concept of Force
Forces are due to interactions. Whenever there is an interaction between objects, forces are produced due to that interaction. There has to be two or more objects so that force can come into play. There are many examples where we can see the effects of force in our real life. For instance, opening and closing a door, pushing a table, playing football or cricket.
Sir Isaac Newton developed three basic laws of motion and in 1687, he published his most important work called “The Philosophiae Naturalis Principia Mathematica”. In this work, he described the three laws of motion as well as the universal law of gravity. Newton’s laws of motion explains how objects behave when forces act upon them.
What are the Scientific Concepts of Force?
In physics, the word force is used to express push or pull in a particular direction. Whenever you push any object, the object goes away from you. This means, a push is when something is made to move away from something. A pull is when something is drawn towards something else.
Mathematically, force is defined as the product of mass and acceleration. Mathematical formula to define force is
F = ma … … …(i)
Where, F = force,
m = mass of the object
a = acceleration of the object.
The SI unit of force is Newton (N)
Effects of Force
The force acting on an object may change its position or shape.
Force can cause an object to move. It can stop a moving object.
Force causes change in direction of an object.
Shape of an object can be changed due to force.
These are some important effects of force which can be felt when we apply force on an object.
When Forces are in the Same Direction
When the force is applied on an object in the same direction, it adds to one another. This means that force applied in the same direction will add up together. So, we can say that the forces are added together when two forces are acting in the same direction. Two people pushing a box together in the same direction is the best example to understand this situation.
To understand this condition, we have shown an example.
When Two Forces Act in Same Direction
Here, both forces 3N and 4N are being applied to the right. Since they are in the same direction, they will combine by addition. So, the resultant force would be 3N + 4N = 7N towards the right.
When Forces Are in the Opposite Direction
Force applied in the opposite direction will be subtracted. Whenever force is applied on an object in the opposite direction, the net force acting on that particular object is the difference between the forces applied.
In other words, we can say that if the two forces act on the same object but in opposite directions, then the net force acting on that object is equal to the net difference between the two forces. Force could be larger or smaller.
To understand this condition, we have shown an example.
When Two Forces act in Opposite Direction
Here, we can see that both the forces 7N and 11N are in the opposite directions. These forces will combine by subtraction. So, 11N - 7N = 4N which will act in the direction of the largest force. So, this object would move towards the right.
Different Types of Forces
There Are Two Different Types of Forces: contact force and non-contact force. Forces that are a result of the physical contact between two objects are called contact forces. Opening a door, kicking a ball and pressing a button are examples of contact force. Frictional force, normal force, spring force, tension force and muscular force are types of contact forces.
Forces which act without having physical contact between two objects are called non-contact forces. In such types of forces, physical contact is not required. Magnetic force, electrostatic force and gravitational force are types of non-contact forces.
Solved Examples
1.Calculate the value of force for an object of $2kg$ mass which is accelerating at $5\dfrac{m}{{{s^2}}}$.
Ans: Given: acceleration $a = 5\dfrac{m}{{{s^2}}}$
Mass of an object is $m = 2kg$
Here, we will use the relation $F = ma$
$\therefore F = (2)(5) = 10N$
So, the value of force is $10N$
2.A constant force acts on an object of mass $5kg$ for a duration of $2\sec $ It increases the velocity of an object from $3\dfrac{m}{s}$ to $7\dfrac{m}{s}$. Determine the force applied.
Ans: Given: mass $m = 5kg$
Time $t = 2\sec $
Initial velocity $u = 3\dfrac{m}{s}$
Final velocity $v = 7\dfrac{m}{s}$
Here, we will use the relation $a = \dfrac{{v - u}}{t}$ to get acceleration,
So, $a = \dfrac{{7 - 3}}{2} = 2\dfrac{m}{{{s^2}}}$
Now, we will use the equation $F = ma$
Therefore, $F = (5)(2) = 10N$
Therefore, the final answer is $10N$
Interesting Facts
Torque is the kind of force that can rotate the objects.
Gravitational forces don’t need to have contact with the objects.
Electromagnetic forces can exert force on objects which are away from them.
Conclusion
We can conclude that in order to apply the force, it is important to know its magnitude, i.e., the amount of force as well as the direction of force. When force is applied in the opposite direction, the total force acting on an object is the net difference between the two forces. We have also discussed contact and non-contact forces along with examples of each type as well as some interesting facts about force.
FAQs on Exploring Forces and Their Effects
1. What is a force and how is it caused in simple terms?
A force is simply a push or a pull on an object. It is caused by an interaction between two or more objects. For a force to be applied, objects must interact with each other. For example, to move a book, you must interact with it by pushing or pulling it.
2. What are the main effects a force can have on an object?
A force can produce several noticeable effects on an object. The primary effects are:
- It can make a stationary object move (e.g., kicking a football).
- It can stop a moving object (e.g., a goalkeeper catching a ball).
- It can change the speed of a moving object, making it faster or slower.
- It can change the direction of motion of an object (e.g., a batsman hitting a cricket ball).
- It can change the shape or size of an object (e.g., squeezing a sponge).
3. What is the difference between contact and non-contact forces? Please provide examples.
The main difference lies in whether the objects need to be physically touching for the force to act.
- Contact Forces: These forces act only when objects are in direct physical contact. Examples include muscular force (lifting a weight) and frictional force (the force that slows down a rolling ball).
- Non-Contact Forces: These forces can act from a distance without any physical contact between the objects. Examples include magnetic force (a magnet attracting iron nails), gravitational force (the Earth pulling an apple downwards), and electrostatic force (a charged comb attracting paper bits).
4. If two forces act on an object from opposite directions, how do we determine the final outcome?
When two forces act on an object in opposite directions, the resulting force, known as the net force, is the difference between the two forces. The object will move in the direction of the larger force. For example, if you push a box with a force of 10 Newtons to the right and a friend pushes it with 7 Newtons to the left, the net force is 3 Newtons (10 N - 7 N) to the right, and the box will move to the right.
5. Why is friction considered a contact force, while gravity is a non-contact force?
This is because of how each force originates. Friction is a force that resists motion and arises specifically from the microscopic interactions between two surfaces that are in direct contact and sliding or trying to slide past each other. Without contact, there is no friction. In contrast, gravity is a fundamental force of attraction between any two objects with mass. It acts over vast distances and does not require the objects to touch. The Earth pulls on the Moon, keeping it in orbit, without any physical connection.
6. How is muscular force an example of a contact force used in our daily lives?
Muscular force is the force generated by the action of muscles in our body. It is a contact force because our muscles must be in contact with our bones to cause movement. We use it constantly in daily activities like walking, lifting objects, writing, and even breathing, where the diaphragm muscle contracts and expands.
7. If an object is not moving, does it mean that no forces are acting on it?
No, this is a common misconception. An object not moving (i.e., being stationary) means that the net force acting on it is zero. This can happen in two ways: either no forces are acting on it, or multiple forces are acting on it in such a way that they cancel each other out. A classic example is a book resting on a table. The force of gravity pulls the book down, while the normal force from the table pushes it up with equal strength. The forces are balanced, so the book remains at rest.
8. Can a force change an object's direction of motion without changing its speed?
Yes, a force can change the direction of an object's motion without altering its speed. The best example of this is an object in uniform circular motion, like a satellite orbiting the Earth. The Earth's gravitational force continuously pulls the satellite towards the center, constantly changing its direction of travel to keep it on a circular path. However, the satellite's speed can remain constant throughout its orbit.
