Question

A truck initially moving with the speed of 30 kmh^-1 , accelerates and moves with the speed of 70 kmh^-1 after 10 sec . Calculate the acceleration of the truck

Answer 1

Given :

• Initial speed of truck (u) = 30km/h
• Final speed of truck (v) = 70km/h
• In time (t) = 10s

To Find :

• Acceleration (a)

Formula Used :

First Equation Of Motion

$\bullet\underline{\boxed{\sf v = u+at}}$

Solution :

Convert km/h to m/s

$\implies{\sf u = 30\: km/h}$

$\implies{\sf 30 \times \dfrac{5}{18} }$

$\implies{\bf u = 8.3 \: m/s }$

$\implies{\sf v = 70 \: km/h}$

$\implies{\sf 70 \times \dfrac{5}{18}}$

$\implies{\bf v = 19.4 \: m/s }$

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$\implies{\sf v=u+at }$

$\implies{\sf a =\dfrac{v-u}{t}}$

$\implies{\sf a =\dfrac{19.4-8.3}{10}}$

$\implies{\bf a = 11.1\:m/s^2 }$

Answer :

Acceleration of truck is 11.1 m/s²

➞ Related Formula

• v = u + at
• s = ut + ½at²
• v² = u² + 2as

Answer 2

Given ,

• Initial velocity (u) = 30 km/hr or 8.3 m/s
• Final velocity (v) = 70 km/hr 19.4 m/s
• Time (t) = 10 sec

We know that ,

The rate of change of velocity is called acceleration

$\large \mathtt{ \fbox{Acceleration (a) = \frac{v - u}{t} }}$

The SI unit of acceleration is m/s²

It is vector quantity

Thus ,

a = (19.4 - 8.3)/10

a = 11.1/10

a = 1.11 m/s²

Hence , the acceleration of the truck is 1.11 m/s²