Question

A car travelling at 20km/h speeds up to 60 km/h in 6 seconds. What is its acceleration​

Answer 1

Given :

• Inital Speed(u) = 20 km/hr

• Final Speed(v) = 60 km/hr

• Time(t)= 6 seconds

To Find :

• Acceleration Produced

Solution :

First of all convert the given units of km/hr into m/sec

For this we've to multiply the given number with $\sf\dfrac{5}{18}$

• Initial speed = 20 km/hr

→ 20 × $\sf\dfrac{5}{18}$

→ $\sf\dfrac{50}{9}$

→ 5.6 m/sec (Approx)

• Final Speed = 60 km/hr

→ 60 × $\sf\dfrac{5}{18}$

→ $\sf\dfrac{50}{3}$

→ 16.7 m/sec (Approx)

$\bigstar \: \boxed{ \sf \: Acceleration = \frac{Change \: in \: velocity}{ Time \: taken} }$

$\longrightarrow \sf \:{ \sf \: Acceleration = \dfrac{Final \: Velocity - Initial \: Velocity }{ Time \: taken} }$

$\bigstar \: \large \: \boxed{ \sf \: a = \frac{v - u}{t} }$

$\longrightarrow \sf \:a = \dfrac{16.7 - 5.6}{6}$

$\longrightarrow \sf \:a = \cancel\dfrac{11.1}{6}$

$\longrightarrow \large \sf \red{\:a = 1.85m {s}^{ - 2} }$

$\therefore$ Acceleration produced is $\sf1.85m {s}^{ - 2}$