Question

A car acquires a velocity of 72 km/hin 10sec starting from rest find ,acceleration,total distance travelled,average velocity​

Answer 1

Given :

• initial velocity = 0 ( rest )

• final velocity = 72 km / hr

( in order to convert it into m / s multiply by 5 /18 )

final velocity= 72 × 5 / 18 = 20 m / s

• time taken = 10 sec

To find :

• acceleration
• total distance
• average velocity

Solution :

(a) acceleration :

Using the I st kinematic equation,

$\boxed{v = u + at}$

here ,

• v = final velocity
• u = initial velocity
• a = acceleration
• t = time taken

As initial velocity of the car is zero ( u = 0 )

$\implies{v = at}$

$\implies{a = \frac{20}{10} }$

$\boxed{a = 2 \frac{m}{ {s}^{2} } }$

(b)total distance :

Using the 2 nd kinematic equation,

$\boxed{s = ut + \frac{a {t}^{2} }{2} }$

here ,

• s = distance

As initial velocity of the car is zero ( u = 0 )

$\implies{s = \frac{a {t}^{2} }{2}}$

$\implies{s = \frac{2 \times 100 }{2} }$

$\boxed{s = 100m}$

(c ) average velocity

$\boxed{Vavg = \frac{displacement}{time} }$

here,

distance = displacement = 100 m

$\implies{Vavg = \frac{100}{10} }$

$\boxed{Vavg = 10 \frac{m}{s} }$

Answer 2

▪ $\underline\mathrm{Given-}$

• $\mathrm{Initial \: Velocity(u) = 0m/s}$
• $\mathrm{Final \: Velocity = 20m/s}$
• $\mathrm{Time = 10sec}$

▪ $\underline\mathrm{To \: Find-}$

• $\mathrm{Acceleration(a) = ?}$
• $\mathrm{Total \: Distance = ?}$
• $\mathrm{Average \: Velocity(av) = ?}$

▪ $\underline\mathrm{Solution-}$

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$\mathrm{1st \: Eqn \: Of \: Motion-}$

$★ \: v = u + at$

▪ $\underline\mathrm{Acceleration-}$

$⟶20 = 0 + a \times 10$

$⟶20 = a \times 10$

$⟶a = \frac{\cancel{20}}{\cancel{10}}$

$⟶a = 2 {m/s}^{2}$

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▪ $\underline\mathrm{2nd\: Eqn \: Of \: Motion-}$

$★s = ut + \frac{1}{2} \: {at}^{2}$

$\underline\mathrm{Initial \: Velocity = 0m/s}$

▪ $\underline\mathrm{Acceleration}$

$⟶s = \frac{ {at}^{2} }{2}$

$⟶s = \frac{2 \times {10}^{2} }{2}$

$⟶s = \frac{2 \times 100}{2}$

$⟶s = \frac{\cancel{200}}{\cancel{2}}$

$⟶s = 100m$

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▪ $\underline\mathrm{Average \: Velocity -}$

$★av = \frac{displacement}{time}$

$⟶av = \frac{100}{10}$

$⟶av = \frac{\cancel{100}}{\cancel{10}}$

$⟶av = 10m/s$

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