NCERT Class 9 Science (Exploration) Solutions
Chapter 1: Exploration Entering the World of Secondary Science
Chapter-wise
Class 9 Science Exploration Chapter 1 Question Answer
Class 9 Science Ch 1 Exploration Entering the World of Secondary Science Question Answer
Exploration Entering the World of Secondary Science Class 9 Questions and Answers (InText)
Pause and Ponder (NCERT Textbook Page No. 4)
Think of a prediction you or your family made recently (for example, the outcome of a cricket match). Was it based on evidence and reasoning or solely on guesswork? How can scientific thinking improve such predictions?
Answer:
Most everyday predictions are often based on guesswork rather than evidence. For example, a family member might say, India will win the cricket match today because it has strong players. This is mainly a general belief and is not based on detailed analysis. Scientific thinking improves such predictions by using evidence, past performance data, pitch conditions, weather, and player statistics. For instance, checking a team’s recent form or a player’s performance on a particular ground makes the prediction more logical and reliable.
Pause and Ponder (NCERT Textbook Page No. 6)
Describe one situation where an approximate answer is good enough, and one where you would need a very exact value.
Answer:
An approximate answer is enough when estimating travel time (e.g., “about 30 minutes”) or daily needs like food quantity.
An exact value is needed in situations like measuring medicine doses or constructing a bridge, where precision is crucial for safety and correctness.
Pause and Ponder (NCERT Textbook Page No. 6)
Choose a real-life object (maybe a pressure cooker or a mobile phone) or a problem (maybe a traffic jam near your school). Make a sketch listing what kind of ideas from physics, chemistry, biology, earth science, or mathematics are involved. Show how at least two branches of science connect with your example.
Answer:
Example: Pressure Cooker
A pressure cooker involves concepts from different branches of science:
- Physics: Heat and pressure increase inside the cooker, raising the boiling point of water and cooking the food faster.
- Chemistry: Cooking involves chemical changes in food, making it softer and easier
to digest. - Mathematics: Used in measuring time, temperature, and the quantity of ingredients.
Connection: Physics and chemistry are connected. Increased pressure (physics) speeds up chemical changes in food (chemistry), resulting in faster cooking. This shows how different branches of science work together in everyday life.
OR
Example: Mobile Phone
A mobile phone involves ideas from different branches of science:
- Physics: Used in electricity, circuits, sound, and electromagnetic waves for communication.
- Chemistry: Used in the battery (chemical reactions that store and supply energy).
- Mathematics: Used in coding, data processing, and signal calculations.
Connection: Physics and chemistry work together-chemical energy in the battery (chemistry) is converted into electrical energy (physics) to operate the phone. This shows how different branches of science are interconnected in real-life objects.
OR
Example: Traffic Jam near School
A traffic jam near school involves concepts from different branches of science:
- Physics: Cars accelerate and decelerate following laws of motion; friction between tyres and road affects stopping distance.
- Mathematics: Statistics calculate average speed and traffic density; graphs show flow patterns during peak hours.
- Earth Science: Vehicle exhaust produces air pollutants, forming smog and contributing to climate effects.
Connection: Physics and mathematics are interconnected. Car motion patterns (physics) enable traffic flow predictions using equations and graphs (mathematics). Thus, both these branches of science together help us understand how traffic conditions affect the environment.
Class 9 Science Chapter 1 Question Answer (Activities)
Activity 1.1: Let Us Model (NCERT Textbook Page No. 2)
Suppose you ride a bicycle from your school to your home. You want to model the time it takes to go home from school. What details would you keep? What details could you ignore? Suggest why ignoring some details may actually be useful?
Answer:
To model the time taken to travel from school to home on a bicycle, the important details like the distance between school and home, speed of the bicycle, total time taken, and road conditions (if significantly affecting speed) need to be considered.
Less important factors like colour of the bicycle, type of clothes worn, surroundings like buildings or trees, brand of the bicycle can be ignored. Ignoring less important details helps in simplifying the situation and focusing on the key factors.
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