Force and Motion Motion, force, and mass

Standard: 8.P.2 The student will demonstrate an understanding of the effects of forces on the motion and stability of an object. (Physical Science)

8.P.2A.1 Plan and conduct controlled scientific investigations to test how varying the amount of force or mass of an object affects the motion (speed and direction), shape, or orientation of an object.

Motion Did the beaver move? What is motion? A change in the position of an object over time. How do you know something has moved? You use a reference point! A stationary (not moving) object such as a tree, street sign, or a line on the road.

What causes an object to move? A FORCE! ALL motion is due to forces acting on objects! What is a force? A push or a pull FORCE MOTION

Can more than one force act on an object at the same time? The total combination of the forces acting on an object is called NET FORCE. YES! Example: Gravity is pulling you down to Earth, the ground is supporting you, and your legs moving you forward as you run during PE. Can more than one force act on an object at the same time? #3 #1 #2

Mass Mass is how much matter is in something. You can physically touch matter. The more matter there is, the more something will weigh. It is not the same as weight -amount of gravity pulling on an object. It’s harder to make a large object move or change the speed and direction of it when it’s moving.

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The amount of matter in an object How much force gravity pulls on an object Yes on Earth, the measurement is the same - once you leave Earth your weight will change, but your mass will remain the same Always constant (same) no matter the location. Weight depends on location of object g, kg, mg Newtons (N) scale Balance

Questions What happens when I throw a baseball and a bowling ball with the same force? Which one speeds up faster and why?

Consider the behavior of colliding objects. Think about this! How is it possible for a 100 lb football player to knock down a 150 lb player? Consider the behavior of colliding objects.

Got It? The smaller player usually must be running faster. Mass makes a difference when two objects collide, but the speed of the objects also matters. Soooooo…… In order for a smaller object to take out a larger object, the smaller object must have greater speed.

Turn and Talk to a Table Mate What is another example of a smaller object taking out or knocking over a bigger object. Record it in your ISN.

Lab: Colliding Balls Observe and compare the 2 types of balls. Record the similarities and differences in a 3 column T chart. Ball 1: Wooden Similarities Ball 2: Metal

Lab Directions: Design and conduct a series of mini experiments w/ the balls. Remember the purpose is to understand what the balls do when they collide. Include trials w/ each of the following. Make sure everyone in your group is participating. (Take turns and/or assign jobs.) Roll the balls toward each other so that they collide. Test wooden ball to wooden ball. Do one fast and one slow, do both slow, do both fast, allow one to be still or stationery. Record your results as a qualitative statement. Repeat the steps w/ a metal and wooden ball.

Colliding Balls Wooden to Wooden Wooden to Metal Ball Types Slow to Slow Slow to Still Fast to Still Fast to Fast Fast to Slow Wooden to Wooden   Wooden to Metal

Lab: Findings What happened when you rolled the 2 wooden balls into each other at the same speed? Slowly? Faster? Different speeds? With one stationery? What happened when you rolled metal and the wooden balls into each other? Describe each set up. Turn and talk to your table about your findings. Compare your data to another groups.

Force and Motion Notes skip at least 2 lines between bullets If an object is in motion and more force is applied to it, the object will begin moving faster. If two objects have the same mass and a greater force is applied to one of the objects, the object which receives the greater force will change speeds more quickly. Example – hit a ball harder, it speeds up

Force and Motion Notes skip 2 lines between bullets If an object must be slowed down quickly, the force applied to the object must be greater than what is needed for a gradual slowing down. Example: bicycle brakes

Force and Motion Notes skip 2 lines between bullets Varying the amount of force applied to a moving object can also change the direction that the object is moving more or less quickly. Example – baseball will change direction when hit by a bat

Mass Notes skip lines between bullets If a heavy (more massive) object is in motion, more force must be applied to get the object moving faster. If the same force is applied to two objects, the object with the smaller mass will change speeds more quickly. For example if a baseball and a bowling ball are thrown with the same force the baseball will speed up faster.

Mass Notes skip 2 lines between bullets In order to slow down or stop a heavier (more massive) object, the force on that object must be greater than for a less massive object. Example – a small car will slow down more quickly than a large truck It is more difficult to change the direction of a heavy moving object, than one that is lighter in mass.