Answer:
A physical change involves a change in physical properties. Examples of physical properties include melting, transition to a gas, change of strength, change of durability, changes to crystal form, textural change, shape, size, color, volume and density.
They can change because the law of conservation of energy allows it to happen, for example when you are sitting, your body is at a potential energy state, meaning you are inert, you are not moving, but when you get up and suddenly start walking or running, that energy is converted to kinetic energy, meaning that you are moving and can be changed back into potential energy if all of a sudden you stop running or walking to rest or sit down. This is just an example of how energy can are transferred multiple ways
Answer:
Explanation:
Given
Two masses 
and 
is released and there is tension T in the string
Suppose a is the acceleration of the system
Therefore from Diagram
For
------1
for m_2 body
-------2
From above two Equation it is said that Tension is greater than m_1g and less than m_2g
momentum= mass × velocity
p= 50×18
momentum= 900 kg m/s
I think it's 16.8 because you multiply 5.6x3=16.8
