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**Please Help! Physics I Midterm Exam in 2 days!**

1. A car travels 95 km to the north at 70.0 km/h, then turns around and travels 21.9 km at 80.0 km/h.

What is the difference between the average speed and the average velocity on this trip? Answer 27 km/h.

2. How many nanoseconds does it take for a computer to perform one calculation if it performs

6.7 × 107 calculations/second? Answer 15 ns.

3. A baseball is hit with a bat and, as a result, its direction is completely reversed and its speed is

doubled. If the actual contact with the bat lasts 0.45 s, what is the ratio of the acceleration to the

original velocity? Answer -6.7 s^-1.

4.A football kicker is attempting a field goal from 44 m out. The ball is kicked and just clears the

lower bar with a time of flight of 2.9 s. If the angle of the kick was 45°, what was the initial speed of

the ball? Answer 21.5 m/s.

5. Find the orbital speed of an ice cube in the rings of Saturn, if the mass of Saturn is 5.67 × 1026 kg

and the rings have an average radius of 100,000 km. Answer 19.5 km/s

6. From what height off the surface of Earth should an object be dropped to initially experience an

acceleration of 0.5400 g? Answer 2298 km.

7. A 23 kg mass is connected to a nail on a frictionless table by a (massless) string of length 1.3 m. If

the tension in the string is 51 N while the mass moves in a uniform circle on the table, how long

does it take for the mass to make one complete revolution? Answer 4.8 s

Thanks so much for helping me. The answers came with the 50 question review, but these are the only questions I just can't seem to wrap my brain around.