Question

An object starting from rest travels 20 m in first 20 m in first 2 sec and 160 m in next 4 sec what will be the velocity and distance covered after 7 sec from the start?

Answer 1

Answer:

70m/s

Explanation:

Initial velocity = u = 0m/s

Distance travelled = s = 20m

Time = 2sec

from second equation of motion

s = ut + 1/2at square

20 = 2a

a = 10m/s square

velocity at the end of 2sec

v = u + at

v = 0+ 10*2

v = 20 m/ s

after 4 sec it cover a distance of 160m

so,

160 = 20*4 + 1/2(a) 4 square

160 = 8a+20

8a = 80

a = 10m/s square

it shows acceleration is uniform

so, velocity at end of 7sec for start

v = u + at

v = 0+10*7

v = 70m/s

The velocity after 7sec from the start is 70m/s