A body starts with some initial velocity.along a straight  line . After 3 s it is found to be at a distance of 15 m from the starting point. At 4 s it is at starting point. What is the initial velocity of the body. Assume constant accleration

Asked by www.nishaantoc | 25th Mar, 2020, 06:11: AM

Expert Answer:

Initial velocity u
t = 3s
s = 15 m 
 
We know, 
s = ut +1/2 at2 
 15 = 3u + 1/2 a(3)2 ... (1) 
 
At 4s body is at starting point
Thus, 
s =0 
Hence, 
0 = 3u +1/2 a(4)2 
 
a equals negative u over 2 ... (2)
Substituting eq(2) in (1), we get, 
 
15 x 4 = 12 u - 9 u
60 = 3 u 
u = 20 m/s

Answered by Shiwani Sawant | 25th Mar, 2020, 12:34: PM

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