Question

9. A particle is moving in a circular path having radius of 20/pi cm. Find the ratio displacement
and distance covered by a body after rotation of
(a) 90° (b) 120° (c) 150° (d) 360° (e) 420°​

Answer 1

Step-by-step explanation:

20/pai=20/22/7=20×7/22=6.36 cm.

length of arc= thita/360 ×2×pai×r ...(formula)

(a)For 90° = 90/360×2×22/7×6.36

=11×6.36/7=9.99 cm.

(b) For 120°= 120/360×2×22/7×6.36

=(2×22×6.36)/21

=13.3 cm.

(c)For 150°=150/360×2×22/7×6.36

=15/9×11/7×6.36

=(15×11×6.36)/63

=16.65 cm.

(d)For 360°= 360/360×2×22/7×6.36

=(2×22×6.36)/7

=39.97 cm.

(e)For 420°=420/360×2×22/7×6.36

=7/3×22/7×6.36

=(22×6.36)/3

=46.64 cm.

Ratios.

For (a) 9.99 : 39.97

(b)13.3 : 39.97

(c)16.65 : 39.97

(d)1

(e)46.64 : 39.97