Which opposes motion

What does red shift mean? When looking at a spectrum of light from a star, how can we tell that the light has undergone What is redshift and blueshift? What is the redshift of the CMB surface? What is the redshift of the Andromeda galaxy? How do scientists know that there is redshift from a star going away and EM waves have changed lengths?

How does redshift differ from blueshift? On the ground we are familiar with friction and how friction acts upon a moving object. We have probably all experienced friction when we rub our hands together. We are very glad of friction when the car in front of us suddenly brakes. Think of the problems we might encounter when we walked or drove if there was no friction force.

However, there are other forces which act in a similar way to friction. Describe the force of friction on stationary and moving objects. Be able to distinguish between the three different types of friction. Identify the four main factors that contribute to friction. It is important to remember that a force is a push or a pull. Forces can give energy to an object and cause it to move, forces can stop the movement of an object, and forces can change the direction of an object.