<h1><strong>MEANING AND TYPES OF FORCE</strong></h1> CONTENT <ol> <li>Definition of Force</li> <li>Mathematical Expression of Force</li> <li>Types of Forces</li> <li>Differences between Gravitational Force and Magnetic Force</li> <li>Uses of Force</li> </ol>   <h2><strong>Definition of Force</strong></h2> Force is any action that moves an object or alters its uniform motion in a given direction. Force is the product of mass of the objects and its acceleration. The greater the mass of the object, the greater the force required to move it. Examples of force are pull, push, tension forces and frictional force between surfaces. <strong>Force is measured in Newton.</strong> <h2><strong>Mathematical Expression of Force</strong></h2> F ά mass × acceleration F = ma, where m = mass and a = acceleration due to gravity <h2><strong>Types of Forces </strong></h2> There are two types of force. These are; <ol> <li>Contact force</li> <li>Non-contact force/force field</li> </ol> <h3><strong>Contact Force </strong></h3>

<h1><strong>CALCULATION OF GRAVITATIONAL FORCE</strong></h1> CONTENT <ol> <li>Definition of Gravitational Force</li> <li>Calculation of Gravitational Forces</li> </ol>   <h2><strong>Definition of Gravitational Force</strong></h2> This is the force with which the earth pulls all objects towards its centre. It is also called force of gravity. The instrument used for measuring gravitational force is called spring balance. <h2><strong>Calculation of Gravitational Forces</strong></h2> The unit of force is Newton (the symbol is N). The unit was named after Sir Isaac Newton who first discovered the facts about gravity. The weight of a body is the force the earth exerts on it. <strong>All forces are measured in Newton.</strong> On the earth surface the universal value of acceleration due to gravity (g) is 9.8m/s² or 10m/s² To calculate gravitational force (Gf). The following formulae are used: 1. F = mg, used for calculation of gravitational force. <strong>Example 1:</strong> Calculate the gravitational force required to pull down a mango fruit of 10kg falling with acceleration of 5m/s². <strong>Solution:</strong> F = mg, where F is unknown, m = 10kg, a = 5m/s² ∴ F = 10 × 5 = 50 N. <strong>Example 2:</strong>

<h1><strong>FRICTION: BALANCED AND UNBALANCED FORCES </strong></h1> CONTENT <ol> <li>Meaning of Friction</li> <li>Uses and Advantages of Friction</li> <li>Disadvantages of Friction</li> <li>How to Reduce Friction</li> <li>How to Reduce Friction</li> <li>Balanced and Unbalanced Forces</li> </ol>   <h2><strong>Meaning of Friction</strong></h2> The force that tries to stop a body from moving is called friction. Friction also means force that opposes motion. Friction can be reduced by lubrication i.e. adding oil and grease placed between the two surfaces in contact. The oil and grease are called lubricants. <h2 style="text-align: center;"><img class="size-full wp-image-36570 aligncenter" src="https://classhall.com/wp-content/uploads/2018/06/protection-from-friction.jpg" alt="Friction; Balanced and Unbalanced Forces - Protection from friction" width="396" height="239" /><strong>Protection from Friction</strong></h2> <span style="color: #008000;">Friction is a force that occurs when one object moves against another. The ceramic tiles on the outside of the space shuttle protect it from the great friction caused when the shuttle re-enters Earth’s atmosphere.</span> <h2><strong>Uses and Advantages of Friction</strong></h2> The following are the uses and advantages of friction: