Question

A motorcycle and a bus are moving with the same momentum. Which of them has greater kinetic energy?

Answer 1

Hint: Linear momentum, often known as translational momentum or simply momentum, is the product of an object's mass and velocity in Newtonian physics. It's a two-dimensional vector quantity with a magnitude and a direction. If m is the mass of an item and v is its velocity (also a vector quantity). Momentum is measured in kilograms metres per second (kgm/s) in SI units.

Complete answer:
The kinetic energy of an item is the energy it has owing to its motion in physics. It is the amount of effort required to propel a body of a given mass from rest to a certain velocity. The body retains its kinetic energy after gaining it during acceleration unless its speed changes. When the body decelerates from its current speed to a condition of rest, it does the same amount of effort. The kinetic energy of a non-rotating object of mass m moving at a speed v is $ \dfrac{1}{2}m{v^2} $ in classical mechanics. Only when v is substantially less than the speed of light is this a fair approximation in relativistic mechanics. The joule is the standard unit of kinetic energy.
Now from the question,
The kinetic energy of the motorbike will be higher. Because the bus and the motorbike have the same momentum, the motorcycle will have a faster speed due to its lesser mass. This is due to the fact that the product of half the mass and the square of the velocity is kinetic energy.
So lesser the mass higher the kinetic energy.

Note:
Due to molecular translation, rotation, and vibration, electron translation and spin, and nuclear spin, a macroscopic body that is stationary (i.e. a reference frame has been chosen to correspond to the body's centre of momentum) may have various kinds of internal energy at the molecular or atomic level, which may be regarded as kinetic energy. According to the special theory of relativity, all of these things contribute to the body's mass. The kinetic energy referred to when describing the motions of a macroscopic body is generally that of the macroscopic movement alone. Internal energies of all kinds, on the other hand, add to a body's mass, inertia, and overall energy.