Question

A car is travelling along the rod at 20 m/s along a road. A child runs out into road 50 m ahead and a car driver steps on a brake pedal. What must the car deceleration be if the car is to stop just before it reaches the child ?

Answer 1

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

$\green{\tt{\therefore{Deceleration\:of\:bus=4\:m/s^{2}}}}$

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

$\green{\underline \bold{Given :}} \\ \tt: \implies Initial \: speed(u) = 20 \: m/s \\ \\ \tt: \implies Final\:speed(v)= 0 \: m/s \\ \\ \tt: \implies Distance(s) = 50 \: m \\ \\ \red{\underline \bold{To \: Find :}} \\ \tt: \implies Deceleration(a) = ?$

• According to given question :

$\bold{As \: we \: know \: that} \\ \tt: \implies v^{2} =u^{2} +2as \\ \\ \text{Putting \: given \: value} \\ \tt: \implies 0^{2} = 20^{2}+2 \times a\times 50 \\ \\ \tt: \implies 0 =400 + 100\times a \\\\ \tt{:\implies -400=100\times a}\\ \\ \tt: \implies a=\frac{-400}{100} \\ \\ \green{\tt: \implies a =-4 \: m/s^{2}} \\ \\ \tt\green{\therefore Deceleration \: of \:bus \: is \: \: 4 \: m/s^{2}} \\ \\ \blue{\bold{Some \: formula \: realted \: to \: this \: topic}} \\ \orange{\tt \circ \: v = u + at }\\ \\ \orange{\tt \circ \: s= ut +\frac{1}{2}at^{2}}$

Answer 2

$</p><p>\huge{\pink{\tt{Hello!!! }}} \\ \\</p><p></p><p></p><p>\tt{\green{Given \: - }}$

$</p><p>\tt{\purple{=>U\: = \:20 \:m/s }} \\ \\ </p><p>\tt{\blue{=>V \:= \:0 \:m/s }} \\ \\ </p><p>\tt{\red{=>S\: =\: 50 \:m }}$

$</p><p>\huge{\fbox {\fbox{\rightarrow {\mathfrak {\orange{{V}^2 = {U}^2 + 2.a.s }}}}}}$

$</p><p>\tt{\purple{Where = >\begin{cases}</p><p></p><p>U & \text{20\: m/s} \\</p><p>\\</p><p>V & \text{0 \: m/s}</p><p>\\ \\</p><p>S & \text{50 \: m }</p><p>\end{cases}}}$

Solving We Get : -

$</p><p>\tt{\orange{\boxed {\boxed {A \: = \: -4 \: m/s. }}}}$

________________________

OTHER RELATED FORMULAS :

$</p><p>\huge{\fbox {\fbox{\rightarrow {\mathfrak {\orange{V = U + 2.a.t }}}}}}$

$</p><p>\huge{\fbox {\fbox{\rightarrow {\mathfrak {\orange{{V}^2 = {U}^2 + 2.a.s }}}}}}$