Question

an object starting from rest covers 20 metres in first 2 seconds and 160 m in next 4 seconds what is its velocity after 7 seconds from the start.explain in easy way​

Answer 1

Answer:

$s = ut + \frac{1}{2} a {t}^{2}$

In first 2 s,

S=20m

$20 = \frac{1}{2} a ({2}^{2} )$

a=10m/s^2

Velocity at the end of 2 seconds is

V=u+at

=0+10×2=20m/s

In next 4 sec,

$s = ut + \frac{1}{2} a'{t}^{2}$

$160 = 20 \times 4 + \frac{1}{2} a'( {4}^{2} )$

80=8a'

a'=10m/s^2

V=u+at

=0+10×7=70m/s