Question

A bus and a car have same kinetic energy .Which of the two is moving fast?Explain.

Answer 1

KE = m v^2 / 2 = same for the bus (m2, v2) and the car (m1, v1 ).
So. m1 v1^2 = m2 v2^2

v1/v2 = sqrt (m2/m1)

As the mass m2 of the bus is more, velocity/speed v1 of the. car is more.

Answer 2

Explanation:

The motion of an object due to its motion is called its kinetic energy. Its formula is given by :

$E=\dfrac{1}{2}mv^2$

m and v is the mass and the velocity of object respectively

Let E₁ and E₂ are the kinetic energies of bus and the car respectively. According to given condition, a bus and a car have same kinetic energy. So,

$\dfrac{1}{2}m_1v_1^2=\dfrac{1}{2}m_2v_2^2$  

$\dfrac{m_1}{m_2}=\dfrac{v_2^2}{v_1^2}$

m₁ and m₂ are masses of bus and car while v₁ and v₂ are velocities of bus and car respectively.

Since, the mass of bus is more than the car,

$m_1> m_2$        

$\dfrac{v_2^2}{v_1^2}>1$

$v_2>v_1$

So, the car is moving is moving faster. Hence, this is the required solution.