Extra Credit Assessment

Master core physics concepts! Motion, forces, energy, and waves. Practice problems included.

Unit 1 Key Points Motion describe where an object is at a given time. We can use position-time graphs to help us understand this.In this graph, the object is moving 6 meters forward at a constant speed for 3 seconds, then it is stopped from 3-5 seconds. It moves back from 5-8 seconds and then stops for the rest of the time. Velocity time graphs show how an object changes speed over a given period of time.In this graph, we can see that the object is speeding up, then moving at a steady speed, then speeding up again before slowing down.Velocity can be calculated by using this equation: v=distance (divide).Objects are also able to accelerate. Acceleration is how speed is changing over time (speeding up or slowing down).Another way to describe motion is by finding an object's momentum. Momentum (p) = mass (m) x velocity (v). Momentum can be increased by speeding up or increasing the size of the object. 1. In this velocity-time graph, when is the object speeding up? A B C 2. Calculate the velocity of an object that has traveled 100 meters in 25 seconds. 2500 m 4 m 0.25 m 3. Two cars of the same mass collide. Car A was driving with a velocity of 25 m and car B was driving with a velocity of 35 m Which car has more momentum? Car A Car B They are the same 4. This is a velocity-time graph. When does this object come to rest? 15 seconds 30 seconds 50 seconds It does not come to a stop Unit 2: Force Newton's Laws of Motion describe how objects move. In his first law of motion, Newton said an object in motion will stay in motion while an object at rest will stay at rest. This is called inertia. Newton's 2nd Law of Motion describes motion with the equation: Force (F) = mass (m) x acceleration (a).Objects that are in freefall experience acceleration due to gravity, which is g=9.8 m on Earth. All objects are experiencing force of some type. The normal force (Fn) is the force that pushes UPWARDS on an object while the force of gravity (Fg) is the force that holds objects DOWNWARD. Applied force (Fa) is the force in the direction of motion. Force of friction (Fu) is the opposing force. Objects that are falling experience Fg down and air resistance (Fair) up.The free body diagram below shows these forces.Forces can be balanced or unbalanced. Balanced forces are equal in opposite directions while unbalanced forces are not equal.The net force is the sum of the forces. Remember, forces in negative directions (left or down) are represented by NEGATIVE NUMBERS! 5. A bowling ball is traveling forward with an applied force of 25 N. The force of friction on the ball is 2 N. Is this balanced or unbalanced? Balanced Unbalanced It is impossible to tell 6. Find force of a 15 kg object moving with an acceleration of 4 m 19 N 3.7 N 60 N 7. What is the net force? -2 N 0 N +2 N Unit 3: Energy All objects have some form of energy. Potential energy describes the energy an object could have. It is dependent on mass and height. We can find gravitational potential energy (GPE) by multiplying mass (m) x gravity (g=9.8) x height (h). In other words GPE=mgh.Kinetic energy depends on velocity and mass. The more mass an objects has, the more KE it has. Also, the more it speeds up, the more KE it has. We can find KE by using this equation: KE=mvv Law of Conservation of Energy says that energy cannot be created or destroyed, it only changes forms or moves into other places. For example, when riding a bike, a person has chemical energy (PE) that helps the person have energy to ride. As the person is moving, its chemical energy is turning into KE.In a system, work must be done to cause motion. Work(w) = force (f) x distance. The more force used, the more work is done. Also, the further the object is moved, the more work is done. As work is done, power is used. Power = work / time (divide). 8. When does the object have the most GPE? A B C D E 9. At what point is the car moving the fastest (most KE)? A B C D E 10. At point C, the height is 10 m. The mass of the car is 5 kg. If gravity = 10, find GPE. 50 J 100 J 500 J 11. At point B the 5 kg (mass) car has a velocity of 20 m Find KE. 1000 J 2000 J 100 J 12. Based on the Law of Conservation of Motion, does the roller coaster have enough energy to make it up the final hill? Yes No Impossible to tell Unit 5: Gravitational Force Gravitational attraction (force) is the attraction between objects moving in a circle. To increase gravitational force, we can increase mass or decrease distance (make objects closer). As an object gets closer to the object it's orbiting, it speeds up (Kepler's Laws).Newton's Law of Gravitational Attraction describes the forces of orbiting objects.Tiny objects also feel force- electrostatic force. Charges will repel or attract, as shown below.Force fields can be drawn to represent the electrostatic force. Force moves INTO the negative charge. 13. Find the gravitational force between a 10 kg object and a 1 kg object that are 5 meters apart. G=6.67x10^-11. 2 N 2.6 x10^11 N 1.2 x10^-11 N 14. A satellite is orbiting Earth. It is moved closer to Earth. What statement is true? Velocity will decrease Fg increases but velocity decreases Both Fg and velocity increase 15. Which shows two charged particles that are repelling? A B Neither Unit 6: Waves Waves are disruptions through media. They can be in many forms including sound and light. There are two major forms of waves: transverse and longitudinal.A transverse waves and its parts are shown below.Waves can meet. This is called interference. Positive and negative interference is described in the image below:Sound waves can be described by loudness and pitch.Light is another type of wave. Light can both reflect and refract. During reflection, light is bouncing off the surface at an angle equal to the angle it comes in (i=r).During refraction, light moves through an object and changes speed.More dense materials have a higher n value and a cause objects to slow more.We can find the speed of light as it moves through objects. v=c / n where c = speed of light(3x10^8 m and n is the index of refraction. 16. Which wave is more high pitched? A B 17. Which wave is most loudest? 1 2 3 18. During constructive interference, what will happen to the sound? Louder Quieter Nothing 19. What causes light to slow down the most? Air Water Glass Diamond 20. Find the speed of light through glass if c= 3x10^8 m and v=c 3x10^8 1.5 m 2 x10^8 m