Question

When a car driver travelling at a speed of 20 m/s applies brakes and brings the car to rest in 40 seconds, then retardation will be *

Answer 1

Answer:

GIVEN

u=20

v=0

t=40

a=?

v=u-at( minus because a is negative)

o=20-(a×40)

40a=20

a=20/40=1/2

retardation =1/2

Answer 2

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

$\green{\tt{\therefore{Retardation\:of\:car=0.5\:m/s^{2}}}}$

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

$\green{\underline \bold{Given :}} \\ \tt: \implies Initial \: speed(u)= 20 \: m/s \\ \\ \tt: \implies Time(t) = 40 \: sec \\ \\ \red{\underline \bold{To \: find :}} \\ \tt: \implies Retardation \: of \: car =?$

• According to given question :

$\tt \circ \: Final \: velocity = 0 \: m/s \\ \\ \bold{As \: we \: know \: that} \\ \tt: \implies v = u + at \\ \\ \tt: \implies 0 = 20 + a \times 40 \\ \\ \tt: \implies - 20 = a \times 40 \\ \\ \tt: \implies a = \frac{ - 20}{40} \\ \\ \green{\tt: \implies a = - 0.5 \: m/ {s}^{2} } \\ \\ \green{\tt \therefore Retardation \: of \: car \: is \: 0.5 { \: m/s}^{2} } \\ \\ \blue{\bold{Some \: related \: formula :} } \\ \orange{\tt \circ \: {v}^{2} = {u}^{2} + 2as} \\ \\ \orange{\tt \circ \: s = ut + \frac{1}{2} {at}^{2} }$