Force — Important Questions

Gravitational force of the Earth on a falling apple

Step 1: Contact forces act only when two bodies are physically touching each other. Step 2: Non-contact forces act between two bodies even when they are NOT in direct contact. Step 3: Friction, muscular force, and tension in a string all require physical contact – they are contact forces. Step 4: Gravitational force acts between the Earth and the apple even though the apple is in the air and not touching the Earth's surface directly. Step 5: Gravitational, electrostatic, and magnetic forces are all non-contact forces.

6 N in the direction of the larger force

Step 1: When two forces act on a body in OPPOSITE directions, we subtract the smaller force from the larger force to find the resultant. Step 2: Larger force = 10 N, Smaller force = 4 N. Step 3: Resultant force = 10 N − 4 N = 6 N. Step 4: The resultant always acts in the direction of the LARGER force. Step 5: Option 14 N is wrong (that is addition, used when forces act in the SAME direction). Option 4 N simply equals the smaller force, which is incorrect.

Mass remains unchanged; force does not affect mass.

Step 1: Force can change the state of motion, direction of motion, speed, and shape/size of a body. Step 2: However, force does NOT change the mass (amount of matter) of a body. Step 3: Mass is a measure of how much matter is present in a body – applying a push or pull does not add or remove matter. Step 4: Even if you squeeze a lump of clay and change its shape, the mass of the clay remains the same. Step 5: This is an important concept: mass is independent of force applied.

Electrostatic force

Step 1: When the plastic comb is rubbed on dry hair, it gains electric charge. Step 2: The charged comb then exerts a force on the uncharged bits of paper nearby. Step 3: This force between a charged body and nearby objects (even without contact) is called electrostatic force. Step 4: It is a non-contact force because the comb does not need to touch the paper bits to attract them. Step 5: Magnetic force acts between magnets or magnetic materials; gravitational force pulls objects downward; muscular force requires physical contact – none of these apply here.