Physics 512. Motion Graphs Review

Transcription

1 Physics 512 Mr. Greenberg Name Test 1-2 Review Motion Graphs Review Type of Motion on a position vs. time graph on a velocity vs. time graph on an acceleration vs. time graph At Rest Moving forward at a constant velocity Moving backward at a constant velocity Speeding up while going forward Speeding up while going backward Slowing down while going forward Slowing down while going backward What does the slope of a distance vs. time graph tell you? What does the slow of a velocity vs. time graph tell you? What does the area between the velocity line and the time axis tell you?

2 Practice Problems 1) A ball rolls down an incline and the following data are recorded. Time (s) Position (cm) a) Make a proper graph of Position vs Time. b) What type of the relationship exists between position and time? c) Describe the motion d) What does the slope at any point represent? What is happening to the slope?

3 Forces and Newton s Laws Review Fnet = ma weight = Fg = mg g = 9.8 m/s 2 a = (vf vi) / t 1 d v t at 2 v v at 2 i f i v v 2ad 2 2 f i Part I: Multiple Choice 1. Which of the following is the unit of force? a) kg b) N c) kg m/s d) m/s 2 2. When you row a boat, you push the water backwards to go forwards. This is an example of the law of a) Inertia b) acceleration c) action and reaction d) gravity 3. A 3 kg mass has an acceleration of 1.5 m/s 2. What is the value of the net force acting on the mass? a) 4.5 N b) 1.5 N c) 2 N d) 0.5 N 4. The net force acting on an object is equal to zero. This means that a) The object must be at rest b) the object must be accelerating c) The object may be in motion d) the object must have no other forces acting on it 5. A 10 kg mass has a 30 N net force acting on it. The size of the acceleration of the mass is equal to a) 300 m/s 2 b) 40 m/s 2 c) 20 m/s 2 d) 3 m/s 2 6. As the mass of an object increases, its inertia. a) increases b) decreases c) remains the same 7. Approximately how much does the 14 kg mass weigh on the surface of the earth? a) 14 N b) 140 N c) 1.4 N d) 24 N 8. A car and truck are going to collide head on. Compared to the force that the truck exerts on the car, the force that the car exerts on the truck is a) less b) more c) the same d) depends on the relative velocities

4 Part II: Show all work and units used! 9. State Newton s Three laws and provide two examples of each: I: II: III: 10. Emily and Mariana are pushing on a 6 kg mass with a force of 8 N and 10 N to the right. (assume the box is on a frictionless surface) a) Draw a free-body diagram showing all the forces acting on the mass b) Calculate the net force acting on the mass and draw a force vector showing its magnitude and direction. c) If the mass started from rest, how fast will it be going after 8 seconds?

5 11. Remington and Justin now pushing on the same 6 kg mass. Remi applies a force of 8 N to the right, while Justin applies a 10 N force to the left. (again, assume frictionless surface) a) Draw a new free-body diagram b) Calculate the net force and draw a force vector showing its magnitude and direction. c) If the mass starts from rest, how fast will it be going when it has traveled 10 meters? 12. An object accelerates from 10 m/s to 25 m/s in 5 seconds when a 30 N net force is acting on it. How much mass does the object have?