Physics Midterm Review

Slide 1: Physics Review

Slide 2: The Scientific Method • Link the process of a police investigation of a car accident with the stages of the scientific method.

Slide 3: • Observation/collection • Hypothesis • Experiments/tests • Interpret/revise hypothesis • Conclusion

Slide 4: • Observation/collection • The investigator examines the crime scene and fills out a report.

Slide 5: • Observation/collection • Hypothesis • Experiments/tests • Interpret/revise hypothesis • Conclusion

Slide 6: • The investigator imagines several likely scenarios that may have led to to the accident. Maybe • Hypothesis the driver was intoxicated, fell asleep or was speeding; maybe mechanical failure or bad weather conditions.

Slide 7: • Observation/collection • Hypothesis • Experiments/tests • Interpret/revise hypothesis • Conclusion

Slide 8: • The investigator might order a blood alcohol level test; check the car • Experiments/tests parts, test drive the car in different weather conditions to replicate the skid marks left by the car.

Slide 9: • Observation/collection • Hypothesis • Experiments/tests • Interpret/revise hypothesis • Conclusion

Slide 10: • The investigator must reexamine evidence and possibly revise his hypothesis. The • Interpret/revise evidence may be hypothesis inconclusive.

Slide 11: • Observation/collection • Hypothesis • Experiments/tests • Interpret/revise hypothesis • Conclusion

Slide 12: • The investigator goes to court, reexamines the evidence, and defends his theory of how the accident occurred. • Conclusion

Slide 13: The Scientific Method • Observation/collection • Hypothesis • Experiments/tests • Interpret/revise hypothesis • Conclusion

Slide 14: What are the basic SI units for : • Newton • N = kgm/s2 • Joule • J = kgm2/s2 • Watt • W = kgm2/s3

Slide 15: What do the following represent? •d • Distance •x • Displacement in the x direction • Displacement in the y •y direction • Mass or meter •m

Slide 16: How about • x • Change in position • x=xf-xi • Change in velocity • v • v=vf-vi • Change in momentum • p • p=pf-pi

Slide 17: Solve • A car travels from city K to city Q (100. km). If the first half of the distance is driven at 50. km/h and the second half is driven at 100. km/h, what is the average speed for the trip? • (67 km/h)

Slide 18: Solve • A car travels from city K to city Q (100. km). If the first half of the time was at 50. km/h and the second half is spent at 100. Km/h, what is the average speed for the trip? • (75 km/h)

Slide 19: Solve • Find the acceleration of an amusement park ride that falls from rest to a speed of 28 m/s in 3.0 s? • (9.3 m/s2)

Slide 20: Solve • Find the acceleration of an Olympic sprinter who runs 100.0 m in 9.74 s. • (2.11 m/s2)

Slide 21: Solve • A bicyclist accelerates from 5.0 m/s to a velocity of 16 m/s in 8 s. Assuming uniform acceleration, what distance does the bicyclist travel during this time interval? • (84 m)

Slide 22: Solve • An aircraft has a landing speed of 302 km/h. The landing area of an aircraft carrier is 195 m long. What is the minimum uniform acceleration required for a safe landing? (-18.0 m/s2)

Slide 23: Solve • An orange is thrown straight up from the ground at a velocity of 8.7 m/s. What is the orange’s velocity at the end of its flight? • (-8.7 m/s)

Slide 24: • What is the acceleration of the orange at its lowest position? What is the orange’s acceleration at its highest position? How high would the orange go, if there was no air resistance?

Slide 25: Solve • Billy travels 4.5 km northeast and 4.5 km northwest. What is Billy’s total distance traveled? What is his displacement? • (9.0 km, 6.4 km north)

Slide 26: Solve • A plane flies 118 km at 15.0o south of east, then flies 118 km at 35.0o west of north. Find the total displacement of the plane. (81 km at 55o north of east)

Slide 27: Solve • In movies people often jump from buildings into pools. If a person jumps from the 10th floor (30.0 m) to a pool that is 5.0 m away from the building, with what initial velocity must a person jump? • (2.0 m/s)

Slide 28: • What is the acceleration of a projectile just before it hits the ground? • (-9.81 m/s2, the same as at any time during the flight)

Slide 29: Solve • A flying, stationary kite is acted on by a force of 9.8 N downward. The wind exerts a force of 45 N at an angle of 50.0o above the horizontal. Find the angle and the force that the string exerts on the kite? • (38 N, 40.o below the horizontal)