PHYSICS REVIEW SHEET 2010 MID-TERM EXAM Concepts And Definitions Definitions of fact, hypothesis, law, theory Explain the scientific method Difference between average and instantaneous speed and speed and velocity Describe Acceleration and Free Fall Distinguish between scalars and vectors Add and resolve vectors into their components Predict impact distances, horizontal and vertical velocities for all projectiles Desiree circular motion and the resultant forces associated with it Explain and apply Newton's three laws Distinguish between weight and mass Calculate and explain the effects of friction Describe air resistance and terminal velocity Use the impulse equation to explain real-life situations Describe and calculate problems using the Law of Conservation of Momentum Relate work, potential energy and kinetic energy to one another Apply the Law of Conservation of Energy Calculate the efficiency of a machine Explain how torque and center of mass affect rotation Explain the Law of Universal Gravity Evaluate the contributions of Galileo and Kepler to the study of Mechanics Sample Problems 1. You want to complete a 500 mile trip in 10 hours. Yet, because of the ever-present construction zones, you only average 40 mph for the first two hours. You then need to stop for lunch, which kills another 1/2 hour. How fast must you drive (on average) to complete the trip on time? 2. If an airplane can go from its top speed of 48 m/s to a taxi speed of 5.5 m/s in 8.37 seconds, how long a runway does it need?
3. How fast is a rock moving as it strikes the pavement if it is dropped from the top of a building that is 223 meters tall? Distance v Tim 60 50 40 30 20 10 0 0 10 20 30 40 Tim e (in m in) 4. When is the car stopped? 5. When is the car speeding up? 6. When is the car slowing down? 7. When is the car traveling at its fastest constant speed? 8. How far did the car travel in the first 15 minutes? 9. How fast is the car traveling at t = 15 minutes? 10. When is the car furthest from the observer? 11. When does the car pass the observer? 12. How far is the car from the observer at t = 40 minutes? 13. How fast is the car traveling at t = 30 minutes?
Velocity vs Tim 20 18 16 14 12 10 8 6 4 2 0 0 10 20 30 40 50 60 Tim e (in seconds 14. When is the car not moving? 15. When is the car moving at its fastest speed? 16. How fast is the car traveling at t = 10 seconds? 17. How far does the car travel in the first ten seconds? 18. When is the car speeding up? 19. When is the car slowing down? 20. When is the car gaining speed at the highest rate? 21. What is the acceleration of the car at t = 56 seconds? 22. What is the acceleration of the car at t = 20 seconds? 23. What is the acceleration of the car at t = 32 seconds? 24. How far does the car travel in the first minute? 25. A motorboat heads due east at 12.0 m/s across a river that flows towards the south with a current of 3.50 m/s. A. What is the resultant velocity of the boat?
B. If the river is 1360 m wide, how long does it take the boat to cross? C. How far downstream is the boat when it reaches the other side? 26. A boy and a girl both swim at 3.0 m/s. They jump into a river 1.0 km across, with a current of 2.0 m/s to the east.. A. The boy faces due north at all times. What is his resultant velocity? B. The girl swims so that she ends up directly across the river. What is her resultant speed?
C. In what direction should she head? D. How many minutes does it take each to cross the river? 27. A cannon is shot horizontally at a speed of 150 m/s off of a cliff 45 meters high. How far away from the base of the cliff will the cannonball land? 28. If a shell is fired from a cannon with a velocity of 20 m/s at an angle of 30, how far will the shell travel away from the cannon?
29. What is the acceleration of a 820 kg car that is being pushed by a truck with a force of 7,000N if the between the tires and the road is 0.87? 30. What is the force of friction acting on a 140 kg box sliding at 2.5 m/s down a 15 ramp if the between the box and the ramp is 0.83? 31. What is the tension in the chain used to hold a 225 kg sign up and to a wall if the chain makes a 25 angle up from horizontal? 32. What force is required to cause a 25 kg sled, moving at 20 m/s to be slowed to 3 m/s in 1.5 seconds?
33. A 65 kg ice skater traveling east at 6.0 m/s runs head-on into an 85 kg skater traveling straight west at 4.5 m/s. At what speed and in what direction do the ice skaters travel if they move together after the collision? 34. A 40 kg projectile leaves a 2000 kg launcher with a speed of 400 m/s. Calculate the recoil velocity of the launcher. 35. A 4.0 kg object traveling westward at 25 m/s hits a 15 kg object at rest. The 4.0 kg object bounces eastward at 8.0 m/s. What is the velocity of the 15 kg object? 36. A bulldozer pushed a large rock with a force of 5000 N over a 20.0 m distance in 40 seconds. How much power does the bulldozer generate?
37. A 4 kg mass is raised to a height and now has a potential energy of 784 J. To what height was it lifted? 38. A car whose mass is 1500 kg has a Kinetic Energy of 168,750 J. What is its speed? 39. How much poweris generated by a 75 kg boy who can run up 20 stairs (each 10.3 cm tall) in 5.25 seconds?