different instances on your motion diagram.

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1 Observe the motion of the ball. What kind of motion is it? How do you know? the same way (don t change the strength of your push!) and keep the ball moving along a straight line. track). Set the ball on the floor at rest and then continually push it with the board for a while. Try to push a) Use a bowling ball and a board (or anything that rolls easily, a billiard ball or a low friction cart on a 3.1 Observe and Represent on the force diagram. What do you notice about these arrows? C) Compare the direction of the isv arrow on the motion diagram to the direction of the unbalanced force I I Draw a motion diagram for the ball. of the unbalanced force. Force, indicate the direction If there is an unbalanced orce exerted on the ball? Nas there an unbalanced Describe these interactions while it is being pushed. interact with the bowling ball List all of the objects that n words. different instances on your he ball that correspond to 3 Draw 3 force diagrams for motion diagram. balance each other? Nhat forces cancel or b) After you agree on how the ball is moving, fill in the table below. Relating Motion Diagrams and Force Diagrams

2 ce:) Draw a motion diagram for the ball. rorce, indicate the direction of the unbalanced force. If there is an unbalanced CtW C in words. Describe these interactions iiagram. orce exerted on the ball? Nas there an unbalanced CACU t\j 0 Nhile it is being pushed. interact with the bowling ball he ball that correspond to 3 List all of the objects that Draw 3 force diagrams for b) After you agree on how the ball is moving, fill in the table below. B instances on your motion balance each other? Nhat forces cancel or moving, push with the board very lightly in the opposite direction to the ball s motion. Try to push the a) Use a bowling ball and a board. This time, set the ball in motion by pushing it once. After it is already same way each time. Observe the motion of the ball. What kind of motion is it? How do you know? 3.2 Observe and Represent

3 3.3 Find a Relationship on the force diagram. F C I, touches your What can you say about the length of the force arrows? b) Now use the relationship you developed in 3.3 to draw a force diagram for the ball at an instant after it a) Predict what the motion of the ball will be like and draw a motion diagram. Explain why you drew it the way youdi A/C4-t LA 4 A it touches the ground. Consider the motion of the ball after it touches your hands. Hold a bowling ball. Imagine now that your friend drops the bowling ball vertically so you have to catch it before 3.4 Test Your Idea GtcW (, r 1 the relationship between unbalanced forces and changes in motion? c) Perform the experiment and record the outcome. Did4 match the prediction? What can you say about tib V W1 4Jv - i tw.f L jt /V4 j 4 how your prediction is based on the relationship you just developed. b) Now predict what will happen if you set the bowling ball in motion and do not touch it after that. Explain e Ac cw$ a) Use your findings in activities 3.1 and 3.2 to formulate how a motion diagram and a force diagram for the same object are related. c) Compare the direction of the zv arrow on the motion diagram to the direction of the unbalanced force KreutterfCostello: Linear Dynamics 3

4 You can check your ideas by actually performing the experiment as it is described and noting how it feels to you. However to check the force diagram and the lengths of the force arrows, you can drop the heavy ball on a c) How is dropping the medicine ball on the bathroom scale like dropping the bowling ball into your d) Now perform the experiment by letting your friend drop the bowling ball into your hands. What did you for the same object direction as the delta v arrow on a motion diagram for that object. We can also say that when all the forces 3.5 Observe and Find a Pattern Newton s first law of motion: We choose a particular object as the object of interest the system. If no other Imagine that you performed the following experiments, and then fill in the table that follows. that results in an unbalanced force. In other words, an object keeps on doing whatever it was doing until it experiences an interaction first law. In the activities above, you determined that an unbalanced force exerted on an object points in the same ri hands? jp//paer. rutqers.edu/pt3/movieslmedballdrop2.mov rutqers.edu/pt3/movies/medballdropl. do to catch it before it touched the ground? What happened to the ball after it touched your hands? mov viewed frame by frame): e) What judgment can you make about your relationship between the motion diagram and force diagram object continues moving at constant velocity (including remaining at rest) as seen by certain observers. objects interact with the system object or if the sum of all the external forces exerted on the system object bathroom scale and observe the reading on the scale. View the following videos (the second one should be exerted on that object are balanced, the delta v arrow is zero. This is a part of the idea behind Newton s is zero (forces in the y direction are balanced and forces in the x direction are balanced), then the system - F I A

5 he back of a cart (a) You steadily push Vh. positive) which direction is Experiment for the cart. for the cart. example. Do you think an unbalanced force exerted on an object causes motion or a change in motion? f) How do you understand the difference between the words motion and change in motion? Give an e) How does your answer to d telate to the rule you developed and tested in 3.3 and 3.4? arrow. Do you see a pattern? Explain. d) Examine the direction of the unbalanced force in each scenario and compare it to the direction of the Ev ) eventually stops. y t slower and slower and he front of the moving cart so that it moves J (c)youpushgentlyon oast. The cart does (b) You stop pushing (1 - aster., \ he cart and let it 1 F,., \J \4 V- moves faster and surface sothat it along a smooth not slow down. vo F.jpcLi Number description (make up numerical Sketch a motion diagram Draw a force diagram values and indicate

6 C) Is the motion diagram consistent with each force diagram? Explain. top of the flight. of its flight. Remember the stomp rockets! b) Draw a force diagram for two instances: right after the ball left your hand and when it is almost at the Liw a) Draw a motion diagram for the motion of the ball after it leaves your hand but before it reaches the top You throw a ball upward. 3.6 Reason