How to take a motion pictures?

I have a nikon d3100 and I'm still learning how to do stuff but I have a project due on Motion and I'm trying to figure out what the shutter speed should be when taking a picture of motion blur and on stop motion as well and what is freeze flash any answers would be helpful

Motion blur can be achieved in two ways. One, the camera is stationary and the subject moves from one side to another. Two, the camera is moved and the subject is stationary. In either case, your shutter speed has to be considerably longer than what is normally needed but determining that shutter speed is product of the speed of the moving object and the distance from the camera.

You would need a shutter speed over a minute if you wanted to blur the motion of a moving tortoise. However to blur the motion of a low flying jet you would need only a fraction of a second. So the relative speed between the the camera and subject makes a difference.

Now comes a bit of a confusing part. The time need to blur the motion is also relative to the camera to subject distance. The greater the distance, the longer you need to keep the shutter open. Imagine you are in a vacant parking lot. You get down on your knees and put your face to the ground and you see a rock 1 foot in front of you. If you move that rock one inch to the left, you can definitely see the change in position. Your camera will also see it. Now, off in the distance, 200' away, your friend is in a car. You note the position. He then moves the car forward one inch. From your unchanged position, can you notice that the car moved? Probably not. The car would need to move a foot or so before you really noticed the difference.

So, we know that the shutter speed required is dependent upon relative speed and relative distance. The slower the relative speed, the longer the shutter speed required. The greater the relative distance, the longer the shutter speed required.

A good easy practice subject is moving cars that pass in front of your home. They will be traveling at a predictable speed (speed limits), it will be repetitive (unless you are a hermit), and their location will be known. Set the camera on a tripod and set the camera to shutter priority. Let the camera correctly calculate the corresponding aperture for each shutter speed you are going to set.

Assuming you want to show a good deal of motion, I would use a wide angle or normal lens (50mm). Telephoto lenses set up close to a roadway are going to give you too narrow of a field of view and are subject to vibrations during long exposures. Also, since you are doing long exposure shots, I would suggest a remote release. For educational purposes, I would start with 1/100th of second and work your way up in time. Depending on your camera, that may be in half stop increments or 1/3 stop increments. Do not change anything on the camera or lens except the shutter speed. Let the camera choose the aperture. Do not move the camera. Do not change the focal length. Increase your exposure time until you get to your longest standard shutter speed (usually 30 seconds). Depending on the available light you might not be able to get to 30 seconds without the using and filters over the lens.

Stop motion with ambient light uses the same principles as above. Except you want the fastest shutter speed possible for the aperture you are using and the available light. I usually use a shutter speed of 1/1000th sec to freeze jets… And that's while panning with them.

Freezing motion with a flash is one of those so simple it gets confusing kind of concepts. Well, let me adjust that some… Simple in theory. With flash photography where the light emitted from the flash unit is your main light, the flash unit becomes your shutter. Think back to those Halloween fun houses where they use a strobe light. What do you see? You see a moving subject but it is segmented. You see a new segment every tenth of a second or so… Far fewer than the the 30 frames motion your eyes and mind are normally used to seeing. That is how flash photography works. We keep the shutter open longer but emit a burst of light so bright and fast that it freezes the exact position of the moving object. Flash units usually emit light from about 1/1, 000th to 1/10, 000 of a second. Despite the fact that the shutter speed on the camera says 1/60th or 1/250th depending on your cameras flash sync speed, your flash is going to be your shutter. The tricky part is getting the flash and camera to fire at the very moment your subject is in the frame. For that, sound and infrared triggers are available. When the noise is detected or when the beam is broken, the system fires the camera and flash. A classic example of this is the water balloon that is popped but the water is still holding the shape.