NCERT Exercise - Q4
Textbook Exercise Problem
The distance between Radha's home and her school is 3250 m. Express this distance into km.
Step-by-Step Verified Solution:
- Step 1: Recall the metric relation: 1 km = 1000 m.
- Step 2: To convert meters into kilometers, divide by 1000.
- Step 3: Distance = 3250 / 1000 = 3.25 km.
Final Answer: 3.25 km
Key Concept / Exam Strategy: Always check if units need division (small to large) or multiplication (large to small).
Generated Exercise #1
Foundation
Question: Give two examples of periodic motion and two examples of rectilinear motion.
Core Concept Tested: Classification of physical types of motion
Mentor Hint: Periodic motion repeats in regular intervals; rectilinear moves along a straight line.
Step-by-Step Solution:
- Step 1: Periodic Motion: (i) Motion of a pendulum of a wall clock, (ii) Motion of the Earth revolving around the Sun.
- Step 2: Rectilinear Motion: (i) An apple falling from a tree, (ii) Sprinters running on a 100 m straight track.
Verified Answer: Periodic: Clock pendulum, planetary orbit. Rectilinear: Falling object, straight track march.
Generated Exercise #2
Intermediate
Question: While measuring the length of a knitting needle, the reading of the scale at one end is 3.0 cm and at the other end is 33.1 cm. What is the actual length of the needle?
Core Concept Tested: Zero error correction in length measurement
Mentor Hint: Actual length = Final reading - Initial reading.
Step-by-Step Solution:
- Step 1: Initial zero-offset reading = 3.0 cm.
- Step 2: Final scale reading = 33.1 cm.
- Step 3: Actual length = 33.1 cm - 3.0 cm = 30.1 cm.
Verified Answer: 30.1 cm
Generated Exercise #3
Intermediate
Question: Why can a pace or footstep not be used as a standard unit of length?
Core Concept Tested: Need for standard SI units in scientific measurement
Mentor Hint: Footstep lengths vary from person to person.
Step-by-Step Solution:
- Step 1: The size of footsteps, paces, and handspans varies from person to person.
- Step 2: Hence, measurements made using body parts lack universal reproducibility.
- Step 3: The International System of Units (SI) was adopted to ensure global consistency.
Verified Answer: Because footstep sizes differ between individuals, leading to inconsistent and subjective measurements.
Generated Exercise #4
JEE-NEET Foundation
Question: A train moves at a uniform speed of 72 km/h. How many meters does it travel in 1 second?
Core Concept Tested: Conversion factor from km/h to SI unit m/s
Mentor Hint: Multiply km/h by 5/18 to get m/s.
Step-by-Step Solution:
- Step 1: 1 km = 1000 m, 1 hour = 3600 seconds.
- Step 2: 1 km/h = 1000 / 3600 = 5/18 m/s.
- Step 3: Speed in m/s = 72 × (5/18) = 4 × 5 = 20 m/s.
- Step 4: Distance in 1 second = 20 meters.
Verified Answer: 20 meters per second
Generated Exercise #5
Advanced HOTS
Question: A cyclist moves along the circumference of a circular track of radius 14 m. If he completes 2 full rounds, calculate the total distance covered. (Take π = 22/7)
Core Concept Tested: Circular motion and perimeter calculation
Mentor Hint: Distance for 1 round = Circumference = 2πr.
Step-by-Step Solution:
- Step 1: Circumference of 1 round = 2 × (22/7) × 14 = 2 × 22 × 2 = 88 m.
- Step 2: For 2 full rounds: Distance = 88 × 2 = 176 m.
Verified Answer: 176 meters