Question

A body, moving with a certain initial velocity and acceleration of 4 ms⁻² , has a displacement of 50 m in 10 s. The final velocity attained by it is

Answer 1

\[ \begin{array}{l} a=4 m / s ^{2} \\ s =50 m \\ t=10 s \end{array} \] using, \( S=u t+\frac{1}{2} a t^{2} \) \[ \begin{aligned} 50 & =u(10)+\frac{1}{2} \times 4 \times 100 \\ u & =-15 m / s \end{aligned} \] using, \( v=u+a t \) \[ \begin{array}{l} v=-15+4(10) \\ v=25 m / s \end{array} \]

Answer 2

Given,

Body is moving with certain initial velocity let u

Acceleration of body, a = 4 ms^-2

displacement of body, s = 50 m

time taken, t = 10 s

To find:

Final velocity attained by body, v = ?

Formulae required:

First equation of motion

v = u + at

Second equation of motion

s = ut + 1/2 a t²

[ Where v is final velocity, u is initial velocity, s is distance covered, a is acceleration, t is time taken ]

Using second equation of motion

→ s = u t + 1/2 at²

→ 50 = u (10) + 1/2 (4) (10)²

→ 50 = 10 u + 200

→ 10 u = 50 - 200

→ u = -150/10

→ u = -15 m/s

Therefore,

Initial velocity of body is -15 m/s.

Now, Using first equation of motion

→ v = u + at

→ v = (-15) + (4) (10)

→ v = -15 + 40

→ v = 25 m/s