Question

A car accelerates uniformly from 18 km h-1 to 36 km h-1 in 5 s. Calculate (i) the acceleration and (ii) the distance covered by the car in that time.​

Answer 1

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Answer 2

☘️ Proper question :

• A car accelerates uniformly from 18 km h^-1 to 36 km h^-1 in 5 s. Calculate (I) the acceleration and (ii) the distance covered by the car in that time.

☘️ Required Solution :

We are given that,

• u = 18 km h^-1 = 5 m s^-1
• v = 36 km h^-1 = 10 m s^-1
• and t = 5 s.

(i) From Eq. (8.5) we have

$\\ \large \sf a = \dfrac{v - u}{t} \\ \\ \sf \: = \frac{10 \: m \: s {}^{ - 1} \: - \: 5 \: m \: s {}^{ - 1} }{5 \: s} \\ \\ \sf \: = 1 \: m \: s {}^{ - 2}$

(ii) From Eq. (8.6) we have

$\\ \sf \: s = u \: t \: + \frac{1}{2} a \: t {}^{2} \\ \\ \sf \: = 5 \: m \: s {}^{ - 1} \times 5 \: s \: + \: \frac{1}{2} \times 1 \: m \: s {}^{ - 2} \: \times \: (5 \: s) {}^{2} \\ \\ \sf \: = 25 \: m \: + \: 12.5 \: m \\ \\ \sf \: = 37.5 \: m$

So, the acceleration of the car is 1 m s^-2 and the distance covered is 37.5 m.