Chapter 8 Force And Pressure Question Answers

Class 8 Ncert Question and Answers, NCERT Class 8 Science Question/Answers / By

Important Terms to Learn Before Starting Making Notes 🗒

Atmospheric Pressure (वायुमंडलीय दबाव): The force exerted by the weight of the atmosphere on a surface.
Contact Force (स्पर्श बल): A force that acts on objects when they are in physical contact with each other.
Electrostatic Force (स्थिर वैद्युत बल): The force between charged objects.
Force (बल): An influence that causes an object to change its motion, direction, or shape.
Friction (घर्षण): The resistance that one surface or object encounters when moving over another.
Gravitational Force (गुरुत्वाकर्षण बल): The force of attraction between two masses.
Gravity (गुरुत्वाकर्षण): The natural force that causes objects to be pulled towards the center of the Earth.
Magnetic Force (चुंबकीय बल): The force exerted by a magnet.
Muscular Force (मांसपेशीय बल): The force generated by muscles in the body.
Non-Contact Force (अ-संपर्क बल): A force that acts on an object without physical contact.
Pressure (दबाव): The force exerted per unit area.
Pull (खींचना): A force that acts to draw something towards the source of the force.
Push (धक्का देना): A force that acts to move something away from the source of the force.

Exercise Question Starts Here: Start Working 🖊️

1. Give Two Examples Each of Situations in Which You Push or Pull to Change the State of Motion of Objects

Push (धक्का देना):

  1. Pushing a swing (झूला): When you push a swing, it starts moving.
  2. Pushing a door (दरवाजा): Pushing a door causes it to open or close.

Pull (खींचना):

  1. Pulling a drawer (दराज): When you pull a drawer, it comes out.
  2. Pulling a rope (रस्सी): Pulling a rope can move a heavy object attached to it.

2. Give Two Examples of Situations in Which Applied Force Causes a Change in the Shape of an Object

  1. Squeezing a sponge (स्पंज): When you squeeze a sponge, it changes shape.
  2. Stretching a rubber band (रबर बैंड खींचना): When you stretch a rubber band, it elongates and changes shape.

3. Fill in the Blanks in the Following Statements

(a) To draw water from a well we have to pull at the rope.

(b) A charged body attracts an uncharged body towards it.

(c) To move a loaded trolley we have to push it.

(d) The north pole of a magnet repels the north pole of another magnet.

4. An Archer Stretches Her Bow While Taking Aim at the Target

(a) To stretch the bow, the archer applies a force that causes a change in its shape.

(b) The force applied by the archer to stretch the bow is an example of muscular force.

(c) The type of force responsible for a change in the state of motion of the arrow is an example of a contact force.

(d) While the arrow moves towards its target, the forces acting on it are due to gravity and that due to friction of air.

5. Identify the Agent Exerting the Force and the Object on Which It Acts

(a) Squeezing a piece of lemon between the fingers to extract its juice:

  • Agent (बल लगाने वाला): Fingers
  • Object (जिस पर बल लगाया गया): Lemon
  • Effect (प्रभाव): Juice is extracted by changing the shape of the lemon.

(b) Taking out paste from a toothpaste tube:

  • Agent (बल लगाने वाला): Fingers
  • Object (जिस पर बल लगाया गया): Toothpaste tube
  • Effect (प्रभाव): Paste comes out of the tube.

(c) A load suspended from a spring while its other end is on a hook fixed to a wall:

  • Agent (बल लगाने वाला): Gravity
  • Object (जिस पर बल लगाया गया): Load and spring
  • Effect (प्रभाव): The spring stretches due to the weight of the load.

(d) An athlete making a high jump to clear the bar at a certain height:

  • Agent (बल लगाने वाला): Muscles of the athlete
  • Object (जिस पर बल लगाया गया): Athlete’s body
  • Effect (प्रभाव): The athlete’s body rises and moves over the bar.

6. How Does the Force Due to Hammering Affect the Piece of Iron?

When a blacksmith hammers a hot piece of iron, the force applied by the hammer changes the shape of the iron, making it into the desired tool or shape.

7. What Force Might Be Responsible for the Attraction Between the Balloon and the Wall?

The force responsible for the attraction between the balloon and the wall is electrostatic force (स्थिरवैद्युत बल). Rubbing the balloon with a synthetic cloth gives it an electric charge, which attracts the uncharged wall.

8. Name the Forces Acting on a Plastic Bucket Containing Water Held Above Ground Level in Your Hand

The forces acting on the bucket are:

  1. Gravitational force (गुरुत्वाकर्षण बल): Pulling the bucket downward.
  2. Muscular force (मांसपेशीय बल): Applied by your hand to hold the bucket upward.

These forces are balanced, so the bucket remains stationary and does not change its state of motion.

9. Name the Two Forces Acting on the Rocket Immediately After Leaving the Launching Pad

  1. Gravitational force (गुरुत्वाकर्षण बल): Pulling the rocket downward.
  2. Thrust (प्रक्षेपण बल): The upward force provided by the rocket’s engines.

10. When We Press the Bulb of a Dropper with Its Nozzle Kept in Water, Air in the Dropper is Seen to Escape in the Form of Bubbles. Once We Release the Pressure on the Bulb, Water Gets Filled in the Dropper. The Rise of Water in the Dropper is Due To

(d) Atmospheric pressure (वायुमंडलीय दबाव).

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