Question

What is the difference between momentum(m×v) and kinetic energy (`1/2mv^2`)of an object?

Answer 1

Its simply just that, kinetic energy is a form of energy, momentum is just a quantity..

Explanation:

Also kinetic energy is in Joules `j` while momentum is in `kgms^-1`

Answer 2

Kinetic energy and momentum have different units. Also, momentum can be a vector quantity. Kinetic energy can only be a scalar quantity.

Explanation:

Both kinetic energy and momentum are physical quantities that can be used describe motion, but there are a number of differences between them.

*Units

Momentum has MKS units of `kg*m/s`
Energy (kinetic or otherwise) has units of `kg*m^2/s^2` or J (for Joules).

*Quantity type (tensor type)

They are different types of tensors.

Energy is a always scalar quantity. Scalars are used to describe physical quantities that only vary in magnitude- i.e. size, quantity or amount.

Momentum can be a scalar or vector. Vectors are used to describe physical quantities that vary in magnitude and direction.

Momentum is denoted with an arrow as `vec p` when it is being used as a vector and `p` when used as a scalar.

The more physics problems you solve, the more knowledge and intuition you'll gain to make decisions on when to use one or the other.

The video below shows two word problems solved that demonstrate some of similarities, differences and connections between kinetic energy and momentum (the physics problem discussion start at 3:56).