Question

An object moving with a speed of 20km/h accelerates with 4km/h^2 and comes in rest. What distance it has covered.

Answer 1

$\blue{\bold{\underline{\underline{Answer:}}}}$

$\green{\tt{\therefore{Distance\:travelled=50\:km}}}$

$\orange{\bold{\underline{\underline{Step-by-step\:explanation:}}}}$

$\green{\underline \bold{Given :}} \\ \tt: \implies Initial \: speed(u)= 20 \: kmh \\ \\ \tt: \implies Acceleration(a) = - 4 \: km {h}^{2} \\ \\ \red{\underline \bold{To \: Find :}} \\ \tt: \implies Distance \: covered(s) = ?$

• According to given question :

$\tt \circ \: Final \: speed = 0 \: kmh \\ \\ \bold{As \: we \: know \: that} \\ \tt: \implies {v}^{2} = {u }^{2} + 2as \\ \\ \tt: \implies {0}^{2} = {20}^{2} + 2 \times ( - 4) \times s \\ \\ \tt: \implies 0 = 400 - 8 \times s \\ \\ \tt: \implies - 400 = - 8 \times s \\ \\ \tt: \implies s = \frac{ - 400}{ - 8} \\ \\ \green{\tt: \implies s = 50 \: km} \\ \\ \bold{Alternate \: method} \\ \tt: \implies v = u + at \\ \\ \tt: \implies 0 = 20 + ( - 4) \times t \\ \\ \tt: \implies - 20 = - 4 \times t \\ \\ \green{\tt: \implies t = 5 \: h} \\ \\ \bold{As \: we \: know \: that} \\ \tt: \implies s = ut + \frac{1}{2} {at}^{2} \\ \\ \tt: \implies s = 20 \times 5 + \frac{1}{2} \times ( - 4) \times {5}^{2} \\ \\ \tt: \implies s = 100 - 50 \\ \\ \green{\tt: \implies s = 50 \: km}$

Answer 2

$\tt{\huge{\pink{Hello!!! }}}$

Correct Question :

An object moving with a speed of 20km/h accelerates with - 4km/h^2 and comes in rest. What distance it has covered.

Solution :

$\tt{\orange {Step-By-Step-Explaination \::- }}$

$\tt{\purple {\leadsto {Formulae \: Used \: - }}}$

$\tt{ \red{ \mapsto{ {v}^{2} \: = {u}^{2} \: + 2as }}}$

Given Values :

• V = 0 m/s.

• U = 20 km/hr.

• A = -4 m/s^2

Substituting and Solving,

$\tt{ \blue{ \mapsto{ {0}^{2} \: = {20}^{2} \: - 8s }}} \\ \\ = s = 50 \: m.$

$\tt{ \red{ \mapsto{ {v}^{2} \: = {u}^{2} \: + 2as }}}$

Additional Formulae :

$\tt{ \red{ \mapsto{s \: = ut \: + \dfrac{1}{2}a {t}^{2} }}}$

$\tt{ \red{ \mapsto{ {v}^{2} \: = {u}^{2} \: + 2as }}}$

$\tt{ \red{ \mapsto{ v \: = u \: + at }}}$