Question

A trunk of mass 1000 kg increases its speed from 36 kmh1 to 72 kmh1. Find it's kinetic energy in physics​

Answer 1

$\bigstar \tt \: {\underline \red {Given }:-}$

• Mass of a truck = 1000 kg
• Initial velocity = 36 km/h
• Final velocity = 72 km/h

$\bigstar \tt \: {\underline \pink {To \: Find }:-}$

• The kinetic energy possessed due to the motion of the truck.

$\bigstar \tt \: {\underline \purple {Solution }:-}$

Wd know that,

$\boxed { \orange\bigstar \sf \green{\:Kinetic \: Energy = \frac{1}{2}m( {v}^{2} - {u}^{2} )}}$

Where,

• m = mass
• v = final velocity
• u = initial velocity

Now,

First of all we will convert the velocities from km/h to m/s.

$\therefore \rm \: initial \: velocity = \frac{5}{18} \times 36 \: \: \: \: \: \: \: \: \: \\ \ \rm \: initial \: velocity = \frac{5}{ \cancel{18}} \times \cancel{36} \: \: ^{2} \: \: \: \: \: \: \: \: \: \: \\ \rm \: initial \: velocity = 5 \times 2 = 10 \: m/s$

$\rm \: And \: final \: velocity = \frac{5}{18} \times 72 \: \: \: \: \\ \rm \: final \: velocity = \frac{5}{ \cancel{18}} \times \cancel{ 72} \: \: \: ^{4} \: \: \: \: \: \: \: \: \\ \rm \: final \: velocity = 5 \times 4 = 20 \: m/s$

Now, putting the values in the formula for calculating kinetic energy, we get,

$\sf \longrightarrow \:K_E = \frac{1}{2} \times 1000 \: ( {20}^{2} - {10}^{2} ) \\ \sf \longrightarrow \:K_E = \frac{1}{2} \times 1000 \:(400 - 100) \\ \sf \longrightarrow \:K_E = \frac{1}{ \cancel2} \times \cancel{1000 }\:^{500} \times 300 \: \: \: \: \: \\ \sf \longrightarrow \:K_E = 500 \times 300 = 150000 \: J$

$\sf \dag \: \red{Kinetic \: Energy (K_E) = 1,50,000 J}$

More to know :-

(i) What is Kinetic Energy?

Ans. The energy possessed by an object due to the motion or virtue of its motion is known as "Kinetic Energy"

(ii) What is the S.I. unit of Kinetic Energy?

Ans. S.I. unit of Kinetic Energy is "Joule" expressed by the alphabet letter "J".