Question

A body covers 200 cm in the first 2 seconds and 220 cm in the next two seconds. What will be its velocity at the end of 7 seconds? Also, find the displacement in 7 seconds.

Answer 1

Assume that the body is under uniform acceleration here. Then, the total distance d traveled after the first t seconds is given by

d=ut+1/2at²

Where u is the initial velocity and a is the acceleration. We put the values of these quantities for the first 2 seconds:

200=2u+2a where u is in cm/s and a is in cm/s/s.

Then at the end of 6 seconds, the total distance travelled is 200+220 = 420 cm. So,

420=6u+18a

Upon solving, this gives u = 115 cm/s and a = -15 cm/s

So velocity at the end of 7 seconds is given by:

v=u+at

= 115 - 105 = 10 cm/s