1. A force is a or a. 2. Forces are described by how they are and in what they are going. 3. forces on an object will change the objects motion.

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1 Name period date assigned date due date returned? 1. A force is a or a. 2. Forces are described by how they are and in what they are going. 3. forces on an object will change the objects motion Forces on an object do not always change the object s motion. forces are equal forces acting in opposite directions. If forces are equal but opposite, the object will move. 5. Work is when you exert a on an object and it. 1

2 6. Work is done if an object moves some 7. Work or no work: 8. In order to work on an object, the force you exert MUST be in the direction as the object s. 2

3 9. The amount of work done depends on the amount of you exert and the the object moves. Work is measured in. WORK = x 10. How much work is done if a 2N of force is used to move a box 4m? 11. A hydraulic lift exerts a force of 12,000N to lift a car 2m. How much work is done on the car? 12. You exert a force of 0.2N to lift a pencil off the floor. How much work do you do if you lift it 1.5m? 13. Who is doing more work to move the barrel? Who has to use more force to move the barrel? 14 A batter walks up to home plate with his bat, stands with his bat in the air, swings his bat, and makes contact with the ball. In which part of this situation is NO work occurring? A batter walks up to home plate with his bat B batter stands with his bat in the air C batter swings the bat D batter makes contact with the ball 3

4 15 Identify a situation in which work is being done. 16 What evidence proves that no work is being done on an object? A turning a page in a science book A an objects remains stationary B reading a science book B an object moves C resting a science book against the wall C an object has mass D holding a science book D an object is heavy 17 Two boxes and their masses are shown below. Which of the following situations shows work being done? A B C D A student is sitting in a chair and holding both boxes. A student is holding the large box 1m above the floor. A student is standing and holding the small box. A student is lifting the small box 0.5m from the floor to a table 4

5 Work Lab Activity Materials block of wood meter stick string Directions For each activity diagram the situation. Make sure you show arrows for your force and the direction of motion of the object. Activity 1 Apply a quick push to the block of wood to make it move 100cm. Activity 2 Apply a force to the block to lift it 100cm. Activity 3 Apply a constant push to the block to move it 100cm Activity 4 Hold a block at the same level for 15 seconds Activity 5 Apply a constant downward force to the desk for 15 seconds Activity 6 Apply a pull to the block to make it move 100cm. 5

6 Ramp or No Ramp Read the instructions for the activity from the power point. Results 17. Force needed to lift the block straight up 18. Height the block was lifted..5m 19. Force needed to pull the block up the inclined plane 20. Length of the inclined plane.5m 21. Force needed to pull the block up the lower inclined plane 22. Length of the inclined plane.5m Calculate the amount of work done in each situation WORK = FORCE x DISTANCE without an inclined plane with an steep inclined plane with an lower inclined plane Questions 21. What are some examples of force? 22. Does applying a force always cause a change in position? 23. Does a change in position always involve a force? 24. Does work always involve a force? 25. Does work always involve a change in position? 26. Explain how an inclined plane affected the amount of work done. 6

7 Your teacher has asked you to set up an experiment on how the angle of a ramp affects the amount of force needed to move a 1kg object. Think about how you would set up that experiment and answer the following questions. 1kg 27 Which of the following pieces of equipment would you use for the experiment? 28 Which of the following data tables should be used to collect the data? I II III IV V ramp triple beam balance spring scale graduated cylinder 1 kg mass A B I, II, and V I, III, and V C I, II, III, and V D I, III, and IV 7

8 Use the following data from a force experiment to make a conclusion. 29 Trial 1: when the ramp was set at 90 degrees, it took 10N of force to move the 1 kg object. Trial 2: when the ramp was set at 60 degrees, it took 8.6N of force to move the 1 kg object. Trial 3: when the ramp was set at 30 degrees, it took 5N of force to move the 1 kg object. First, label the diagrams for trial 2 and 3 to illustrate these results. Trial 1 has already been done for you as an example. Trial 1 Trial 2 Trial 3 10N 1 kg What conclusion can you make from this data? Make sure you write in complete sentences. 8

9 Extension: The equation for work is: work= force x distance Using this equation, calculate how much work is being done in each situation. Remember, the unit for work is joules (J). 1. A man is pushing on a wall with 50N of force. The wall does not move (0m). How much work is he doing? N x m = J 2. A boy pedaled his bike for 1500m and used a total of 100N of force. How much work did he do? N x m = J 3. Two friends went on a boat ride on the Nueces River. One boy did most of the rowing. He rowed for 300m and used 75N of force. How much work did he do? N x m = J 4. The GWJH cheerleaders were doing a lift. The girl in the middle used 43N of force to hold up the other girl. Once up on her shoulders, the girl did not move at all (0m). How much work was done? N x m = J 9