Question

b. A car is moving with a uniform velocity of 45 km/h. Find the kinetic energy of an object of mass 35 kg kept in the car.

Answer 1

$\large{\sf \underline{Solution- }}$

Here it is given that,

• Velocity = 45 km/h

$\rm\implies \: 45 \times \dfrac{5}{18} = \dfrac{25}{2} \: m/s$

➢ We have to find the kinetic energy of an object of mass 35 kg kept in the car.

• Mass of object = 35 kg

We know,

$\rm \implies \: \boxed{ \rm kinetic \: energy = \tt \dfrac{1}{2} \: m \: v ^{2} }$

Here,

• m stands for mass of object
• v stands for volocity

$\rm \implies \: \rm k_e = \tt \dfrac{1}{2} \times 35 \times\left(\dfrac{25}{2} \right)^{2}$

$\rm \implies \: \rm k_e = \tt \dfrac{35}{2} \times\left(\dfrac{25}{2} \right)^{2}$

$\rm \implies \: \rm k_e = \tt \dfrac{35}{2} \times \dfrac{625}{4}$

$\rm \implies \: \rm k_e = \tt \dfrac{21875}{8}$

$\rm \implies \: \rm k_e = \boxed{\sf 2734.378 \: joule}$