An object starts from rest at x = 0 m and t = 0 s. It moves with constant acceleration 4 m/s² along x axis. What is its average velocity between time 2 s and 6 s?

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RRB ALP Electrician 22 Jan 2019 Official Paper (Shift 3)

Answer 1

Concept:

Equation of motion:

Equations of motion of kinematics describe the basic concept of the motion of an object such as the position, velocity, or acceleration of an object at various times.
These three equations of motion govern the motion of an object in 1D, 2D, and 3D.
Three equations: v = u + at, s = ut + 0.5 at², 2as = v² - u²
Here, u = initial velocity, v = final velocity, s = displacement, t = time
Under the influence of gravity, acceleration a is replaced by acceleration due to gravity g.

Calculation:

Given,

Initial velocity, u = 0 m/s, Acceleration, a = 4 m/s²

From the first equation of motion, v = u + at

at t = 2 s, v = 0 + 4 × 2 = 8 m/s

So, the velocity is 8 m/s at t = 2 s.

From the second equation of motion,

s = ut + 0.5 at²

We need to calculate the displacement of time interval (6 s to 2 s)

Now, s = 8 × 4 + 0.5 × 4 × 4²

s = 64 m

The average velocity can be calculated as,

Hence, What is its average velocity between time 2 s and 6 s is 16 m/s.