Question Bank
Fresh questions, deliberately different from the textbook's own exercises. Write your answers on paper first, then reveal each answer to check.
A · Fill in the blanks 10 marks
- A length is expressed in two parts — a number and a ______________.
- Deepa's mother calls a handspan ______________.
- The SI unit of length is the ______________.
- 1 km = ______________ m.
- 1 cm = ______________ mm.
- The smallest length that can be measured with a 15-cm scale is 1 ______________.
- To measure a curved line, we can use a flexible tape or a ______________.
- When distance is stated with respect to a fixed point, the point is called a ______________ point.
- Motion to and fro about a fixed position is called ______________ motion.
- Motion that repeats its path after a fixed interval of time is called ______________ motion.
B · True or false 10 marks
- A handspan is a standard unit of length.
- 1 m = 100 cm.
- The symbol for metre should be written as "M" or "mts".
- While reading a scale, the eye should be directly above the point being read.
- A scale with a broken end cannot be used for measurement.
- A passenger sitting in a moving bus is at rest with respect to the bus.
- The motion of a swing is circular motion.
- An orange falling from a tree shows linear motion.
- Circular motion is a kind of periodic motion.
- 1 inch = 2.54 cm.
C · Match the following 6 marks
| # | Column A | Column B | |
|---|---|---|---|
| 1 | Distance between two cities | (a) | Circular motion |
| 2 | Thickness of a coin | (b) | Oscillatory motion |
| 3 | Merry-go-round | (c) | Linear motion |
| 4 | Swing | (d) | Reference point |
| 5 | March-past on Republic Day | (e) | Kilometre |
| 6 | Delhi on a kilometre stone | (f) | Millimetre |
D · Short answers 5 × 2 = 10 marks
D1 Why do we need standard units of measurement?
Body-part units like the handspan, foot or stride differ from person to person, so the same length gives different numbers — as when five friends measured one table as 13 to 14 handspans. When people travelled between places with different unit systems, this caused confusion, so countries adopted standard SI units, in which the same length measured by anyone gives the same result.
D2 How will you measure the length of an object with a scale whose zero mark is broken?
Place the object so that one end lines up with any clear full mark, say 1.0 cm. Read the mark at the other end, say 10.4 cm. Subtract: length = 10.4 cm − 1.0 cm = 9.4 cm.
D3 How can you measure the length of a curved line?
Use a flexible measuring tape, or place a thread carefully along the curved line, marking where it starts and ends. Then straighten the thread and measure the marked length with a metre scale.
D4 What is a reference point? Explain with the kilometre-stone example.
A reference point is a fixed object or point with respect to which distance or position is stated. When Padma read "Delhi 70 km" and then "Delhi 60 km" on kilometre stones, Delhi was the reference point — the stones told her distance from Delhi, which was decreasing as she travelled.
D5 Distinguish between circular motion and oscillatory motion, with one example each.
In circular motion, an object moves along a circular path, like an eraser whirled on a thread or a merry-go-round. In oscillatory motion, an object moves to and fro about a fixed position, like a swing or a hanging eraser pulled aside and released. Both are periodic.
E · Long answers 2 × 5 = 10 marks
E1 Describe the correct way of measuring the length of an object with a scale. Include the right tool, placing the scale, position of the eye, broken scales, and how to write the result.
- Choose an appropriate scale — a 15-cm scale for a pencil, a metre scale or measuring tape for a room's height, a flexible tape for curved objects like a tree's girth.
- Place the scale in contact with the object, along its length — not tilted away from it.
- Keep your eye directly above the point where you read the scale; looking from the side gives a wrong reading.
- If the zero mark is broken or unclear, start from another full mark (e.g. 1.0 cm) and subtract it from the reading at the other end (10.4 − 1.0 = 9.4 cm).
- Write the result as a number and a unit, with a space between them, the unit symbol in lowercase, no "s" for plural and no full stop: e.g. 9.4 cm.
E2 Explain motion and rest using a reference point. Why can the same passenger be both at rest and in motion? Then describe the three types of motion with examples.
Motion and rest: an object is in motion if its position changes with respect to a reference point with time; it is at rest if its position does not change with respect to the reference point with time.
The bus example: Deepa saw the passengers sitting in the same seats a minute later. Taking herself or the bus as the reference point, they were at rest. Taking a building outside as the reference point, they (and the bus) were in motion. So the same passenger is at rest or in motion depending on the reference point chosen.
Types of motion:
- Linear — along a straight line: a dropped eraser, an orange falling from a tree, a march-past.
- Circular — along a circular path: an eraser whirled on a thread, a merry-go-round.
- Oscillatory — to and fro about a fixed position: a swing, a hanging eraser released after being pulled aside, a metal strip pressed to a table.
Circular and oscillatory motions repeat after a fixed interval of time, so they are periodic.
F · HOTS 2 × 3 = 6 marks
Higher-order thinking. Reason it out rather than recalling a fact.
F1 You are inside a ship with no windows, moving at a constant speed in a straight line on a calm sea. Your friend says, "We are not moving at all." Using the chapter's idea of a reference point, explain who is right.
Both views can be right — it depends on the reference point. Inside the windowless ship, every object you can see (walls, chairs, people) moves along with you, so with respect to the ship you are at rest — and with nothing outside to compare with, you can't tell you are moving. But with respect to the shore or the seabed, your position is changing with time, so you are in motion. Motion only has meaning once a reference point is chosen.
F2 Tasneem wants to make her own metre scale. She is choosing between plywood, paper, cloth, stretchable rubber and steel. Which should she avoid and why? Which is the best choice?
She should not use stretchable rubber or cloth — they stretch or shrink, so the same length would give different readings each time, defeating the purpose of a standard scale. Paper is also a poor choice: it tears, folds and can change with moisture. Plywood or steel are good choices because they are rigid and keep the same length; steel is the most durable. (This answers textbook question 12.)
G · Textbook exercises — worked answers
The chapter's own "Let us enhance our learning" questions. Try each one first, then open it.
G1 Q1. Match lengths with suitable units.
Distance between Delhi and Lucknow → kilometre · Thickness of a coin → millimetre · Length of an eraser → centimetre · Length of school ground → metre.
G2 Q2. True or False.
(i) T — straight road, straight-line motion. (ii) T — that is the definition of motion. (iii) F — 1 km = 1000 m = 1,00,000 cm.
G3 Q3. Which is not a standard unit?
(iv) handspan — it differs from person to person.
G4 Q4. Smallest value measured by different scales.
| Scale / tape | Smallest value (typical) |
|---|---|
| 15-cm scale | 1 mm |
| Metre scale | 1 mm or 1 cm |
| Tailor's tape | 1 mm or 0.5 cm |
| Long measuring tape | 1 cm |
Check your own scales — the smallest value is the gap between two neighbouring marks.
G5 Q5. 1.5 km in metres.
1 km = 1000 m, so 1.5 km = 1.5 × 1000 = 1500 m.
G6 Q6. Curved base of a tumbler or bottle.
Wrap a thread once around the curved base, mark where it meets, straighten it and measure with a scale (or use a flexible tape). Record with the unit, e.g. 22.5 cm (your value will depend on the tumbler).
G7 Q7. Height in m, cm and mm.
Example: height = 1.42 m = 142 cm (× 100) = 1420 mm (× 10). Measure your friend standing against a wall and convert the same way.
G8 Q8. Coins along a notebook side.
Estimate first, then measure: if the notebook side is 24 cm and a coin is 2.4 cm across, you need 24 ÷ 2.4 = 10 coins. Compare this with your estimate.
G9 Q9. Two examples each of linear, circular and oscillatory motion.
Linear: a car on a straight road; an apple falling from a tree. Circular: a merry-go-round; blades of a ceiling fan. Oscillatory: a swing; the pendulum of a clock.
G10 Q10. Objects best measured in mm, cm and m.
| Unit | Objects |
|---|---|
| mm | Thickness of a coin, pencil lead, an ant |
| cm | Pencil, eraser, notebook |
| m | Classroom, cloth for a uniform, school ground |
G11 Q11. Rollercoaster (Fig. 5.19) — types of motion.
The track slopes straight down from the start, goes round a loop, then runs out straight to F.
- Straight sloping part at the start (from A towards the loop) → linear motion.
- Round the loop → circular motion.
- Straight part after the loop, out through F → linear motion.
G12 Q12. Materials for a home-made metre scale.
She should not use stretchable rubber or cloth (they stretch/shrink, so lengths would change), and paper is also unsuitable (tears and crumples). Plywood or steel are rigid and keep their length.
G13 Q13. Card game on unit conversion.
Example: make pairs of cards — "1 km" / "1000 m", "1 m" / "100 cm", "1 cm" / "10 mm", "1.5 km" / "1500 m", "2.5 m" / "250 cm". Shuffle face-down; players turn over two cards and keep them if they are equal lengths. The player with the most pairs wins.
Marks summary
| Section | Questions | Marks |
|---|---|---|
| A · Fill in the blanks | 10 | 10 |
| B · True / False | 10 | 10 |
| C · Match the following | 6 | 6 |
| D · Short answer | 5 | 10 |
| E · Long answer | 2 | 10 |
| F · HOTS | 2 | 6 |
| Total | 35 | 52 |
Section G (textbook exercises) is for practice and is not counted in the marks.