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Calculate, correct to 3 significant figures, the circumference of a circle with: (i) radius 7 cm (ii) radius 10 cm (iii) radius 12 cm.
Formula for circumference is C = 2 x π x r, taking π = 22/7: (i) For r = 7 cm: C = 2 x (22/7) x 7 = 44 cm = 44.0 cm (to 3 significant figures). (ii) For r = 10 cm: C = 2 x (22/7) x 10 = 440 / 7 = 62.857... cm = 62.9 cm (to 3 significant figures). (iii) For r = 12 cm: C = 2 x (22/7) x 12 = 528 / 7 =Read more
Formula for circumference is C = 2 x π x r, taking π = 22/7:
(i) For r = 7 cm: C = 2 x (22/7) x 7 = 44 cm = 44.0 cm (to 3 significant figures).
(ii) For r = 10 cm: C = 2 x (22/7) x 10 = 440 / 7 = 62.857… cm = 62.9 cm (to 3 significant figures).
(iii) For r = 12 cm: C = 2 x (22/7) x 12 = 528 / 7 = 75.428… cm = 75.4 cm (to 3 significant figures).
For more NCERT Solutions of Class 9 Ganita Manjari Chapter 6 Measuring Space: Perimeter and Area Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/maths/ganita-manjari-chapter-6/
See lessCalculate the length of the arc of a circle if: (i) the radius is 3.5 cm and the angle at the centre is 60°, and (ii) the radius is 6.3 m and the angle at the centre is 120°.
Arc length formula is l = 2 x π x r x (θ / 360). (i) Given r = 3.5 cm = 7/2 cm, θ = 60°: l = 2 x (22/7) x (7/2) x (60/360) = 22 x (1/6) = 11/3 cm = 3.67 cm. (ii) Given r = 6.3 m = 63/10 m, θ = 120°: l = 2 x (22/7) x (63/10) x (120/360) = (44/7) x (63/10) x (1/3) = (44 x 9) / (10 x 3) = (44 x 3) / 10Read more
Arc length formula is l = 2 x π x r x (θ / 360).
(i) Given r = 3.5 cm = 7/2 cm, θ = 60°:
l = 2 x (22/7) x (7/2) x (60/360) = 22 x (1/6) = 11/3 cm = 3.67 cm.
(ii) Given r = 6.3 m = 63/10 m, θ = 120°:
l = 2 x (22/7) x (63/10) x (120/360) = (44/7) x (63/10) x (1/3) = (44 x 9) / (10 x 3) = (44 x 3) / 10 = 132/10 = 13.2 m.
For more NCERT Solutions of Class 9 Ganita Manjari Chapter 6 Measuring Space: Perimeter and Area Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/maths/ganita-manjari-chapter-6/
See lessFind the perimeter of a sector (i.e., the curved portion as well as the two straight portions) of a circle of radius 14 cm and sector angle 75°.
Radius r = 14 cm, sector angle θ = 75°. Curved arc length l = 2 x π x r x (θ / 360): l = 2 x (22/7) x 14 x (75/360) l = 88 x (5/24) = 55 / 3 cm = 18.33 cm. A sector is enclosed by the curved arc and two straight boundary radii. Total perimeter = l + 2r = (55/3) + 2 x 14 = 55/3 + 28 = (55 + 84) / 3 =Read more
Radius r = 14 cm, sector angle θ = 75°.
Curved arc length l = 2 x π x r x (θ / 360):
l = 2 x (22/7) x 14 x (75/360)
l = 88 x (5/24) = 55 / 3 cm = 18.33 cm.
A sector is enclosed by the curved arc and two straight boundary radii.
Total perimeter = l + 2r = (55/3) + 2 x 14 = 55/3 + 28 = (55 + 84) / 3 = 139 / 3 cm = 46.33 cm (or 46 1/3 cm).
For more NCERT Solutions of Class 9 Ganita Manjari Chapter 6 Measuring Space: Perimeter and Area Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/maths/ganita-manjari-chapter-6/
See lessFor a ball moving on a smooth frictionless surface, choose the appropriate option that will make the following statements physically correct. (i) If no net force is applied on the ball, the velocity of the ball will remain the same/increase/decrease. (ii) If a net force is applied on the ball in the direction of its motion, the magnitude of the velocity of the ball will remain the same/increase/decrease. (iii) If a net force is applied on the ball in a direction opposite to the direction of its motion, the magnitude of the velocity of the ball will remain the same/increase/decrease.
In (i), according to Newton's first law, an object continues moving at constant velocity without external force, so it will remain the same. In (ii), a forward net force causes acceleration in the direction of motion, so the magnitude of velocity will increase. In (iii), an opposing net force createRead more
In (i), according to Newton’s first law, an object continues moving at constant velocity without external force, so it will remain the same. In (ii), a forward net force causes acceleration in the direction of motion, so the magnitude of velocity will increase. In (iii), an opposing net force creates negative acceleration opposing motion, so the magnitude of velocity will decrease.
For more NCERT Solutions of Class 9 Science Exploration Chapter 6 How Forces Affect Motion Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-6/
See lessUsing a horizontal force F, a table is moved across the floor at a constant velocity. How much is the frictional force exerted by the floor on the table?
Since the table moves across the floor at a constant velocity, its acceleration is zero. By Newton's first law of motion, the net external horizontal force acting on the table must be zero. Therefore, the opposing frictional force exerted by the floor on the table must be exactly equal in magnitudeRead more
Since the table moves across the floor at a constant velocity, its acceleration is zero. By Newton’s first law of motion, the net external horizontal force acting on the table must be zero. Therefore, the opposing frictional force exerted by the floor on the table must be exactly equal in magnitude to the applied horizontal force F, acting in the opposite direction.
For more NCERT Solutions of Class 9 Science Exploration Chapter 6 How Forces Affect Motion Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-6/
See less