Question

A car increase its speed from 20 km/hr to 40 km/hr in 10 sec find its acceleration

Answer 1

Solution :-

Given that

Initial velocity (u) = 20 Km/h

Final velocity (v) = 40 Km/h

Time (t) = 10 seconds

Acceleration (a) = ?

Convert units of 'u' and 'v' into m/s

Initial velocity (u) = 20 * 5/18

= 10 * 5/9

= 50/9 m/s

Final velocity (v) = 40 * 5/18

= 40 * 5/18

= 20 * 5/9

= 100/9 m/s

So, u = 50/9 m/s

v = 100/9 m/s

$\boxed{ \bf a = \dfrac{v - u}{t}}$

By substituting the values

$\sf a = \dfrac{ \frac{100}{9} - \frac{50}{9} }{10}$

$\sf \implies a = \dfrac{ \frac{100 - 50}{9}}{10}$

$\sf \implies a = \dfrac{ \frac{50}{9}}{10}$

$\sf \implies a =\dfrac{50}{9} \div 10$

$\sf \implies a =\dfrac{50}{9} \times \dfrac{1}{10}$

$\sf \implies a =\dfrac{5 \cancel{0}}{9\cancel{0}}$

$\sf \implies a =\dfrac{5}{9}$

Therfore Acceleration = 5/9 m/s²