Question

A body travels 200cm in the 1st 2 sec and 220cm in the next 5 sec. Calculate the velocity at the end of 7th sec

Answer 1

Answer:

10cm/s

Explanation:

Let the initial velocity = u

Let the acceleration = a

Distance traveled in 4 sec = S6

Following the equation s =ut + at2/2

S6 = 4u + a36/2

= 6u+18a

Distance covered in 2 sec = S2 

= 2u + 4a/2

=2u+2a = 200          

u+a = 100  -- eq(1)   

Distance covered in 2 to 6s = 220cm

S6-200 = 220

6u + 18a = 420       

u+3a = 70  -- eq(2)

From 1 and 2

a = -15 & u=115

velocity after 7 sec = V7

V7 = u + at

=115 - 15 ×7

= 10cm/sec

Thus, the velocity  at the end of 7th sec is 10cm/s