An object starts from rest at x = 0 m and t = 0 s. It moves with a constant acceleration of 2m/s² along the x–axis. What is its average velocity between time 1 s and 5 s?

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Question

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RRB ALP Electrician 22 Jan 2019 Official Paper (Shift 1)

Answer 1

Concept:

Calculation:

Given:

Time interval = 5 s & 1 s, Initial velocity u = 0, and, Acceleration a = 2 m/s²

When an object starts from rest, then the total distance covered in time 1 sec and 5 sec is,

s = ut + 1/2 at2

Object is at rest, so, u = 0 m/s.

\(s_2 - s_1 = \frac12 a(t_2^2-t_1^2)\)

\(s_2 - s_1 = \frac12 \times 2(5^2-1^2)\)

s₂ - s₁ = 24 m

Total time taken, t = t₂ - t₁ = 5 - 1 = 4 sec

Average velocity = total displacement/ total time duration

Average velocity = 24/4 = 6 m/s

Average velocity between time 1 s and 5 s = 6 m/s