Question 114: Work, Energy and Power & Circular Motion

Question

A huge circular arc of length 4.4 ly subtends an angle '4s' at the centre of the circle. How long it would take for a body to complete 4 revolution if its speed is 8 AU per second?
Given : 1 ly = 9.46 $$	imes$$ 10
15
m
1 AU = 1.5 $$	imes$$ 10
11
m

Accepted Answer

$$R = {l \over 	heta }$$
Time $$ = {{4 	imes 2\pi R} \over v} = {{4 	imes 2\pi } \over v}\left( {{l \over 	heta }} ight)$$
put l = 4.4 $$	imes$$ 9.46 $$	imes$$ 10
15
v = 8 $$	imes$$ 1.5 $$	imes$$ 10
11
$$	heta  = {4 \over {3600}} 	imes {\pi  \over {180}}$$ rad.
we get time = 4.5 $$	imes$$ 10
10
sec.

Answer

4.1 $$	imes$$ 10
8
s

Answer

4.5 $$	imes$$ 10
10
s

Answer

3.5 $$	imes$$ 10
6
s

Answer

7.2 $$	imes$$ 10
8
s

Work, Energy and Power & Circular Motion

A huge circular arc of length 4.4 ly subtends an angle '4s' at the centre of the circle. How long it would take for a body to complete 4 revolution if its speed is 8 AU per second? Given : 1 ly = 9.46 $\times 10 15 m 1 AU = 1.5 \times$ 10 11 m

Choose the correct answer: