Question

an object starting from rest travels 20m in 1st 2 seconds and 160m in next 4 seconds .

what will be velocity after 7 seconds from start?​

Answer 1

Explanation:

hope you get the solution

Answer 2

Explanation:

$\huge\bf{\mid{\overline{\underline{ANSWER:-}\mid}}}$

$\huge\bold{GIVEN:-}$

Object travels 20 m in first two secs

S = ut + 1/2 at^2

As it starts from rest..

u = 0

S = 1/2 at^2

20 = 1/2 × a × (2)^(2)

a = 40 / 4

a = 10 m/s^2

Now We'll use formula for displacement in nth second..

$S_n = u + \frac{1}{2} \times a \times (2n -1) \\ \\ S_7 = Displacement \: at \: 7th \: second \\ \\ S_7 = \frac{1}{2} \times 10 \times (2(7) - 1) \\ \\ S_7 = \frac{1}{\cancel{2}} \times \cancel{10} \times (13) \\ \\ 5 \times 13 \\ \\ \boxed{65 m}$

$v = u +at \\ \\ v = 10 (7) \\ \\ \huge\boxed{ v = 70 m/s}$