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Bell Ringer Average Speed Louise runs the first half of a race at 5 miles per hour. Then she picks up her pace and run

Answer Assume the course is 20 miles long. Louise needs 2 hours to run the first 10 miles (the first half of the course) and 1 hour to run the last 10 miles (the last half), meaning she needs 3 hours to run the total of 20 miles. Therefore, her average speed is 6.7 miles per hour. . Review. MassMa

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Bell Ringer Average Speed Louise runs the first half of a race at 5 miles per hour. Then she picks up her pace and run

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    1. Bell Ringer Average Speed  Louise runs the first half of a race at 5 miles per hour. Then she picks up her pace and runs the last half of the race at 10 miles per hour. What is her average speed on the course? Hint: The answer is not 7.5 miles per hour.

    2. Answer Assume the course is 20 miles long. Louise needs 2 hours to run the first 10 miles (the first half of the course) and 1 hour to run the last 10 miles (the last half), meaning she needs 3 hours to run the total of 20 miles. Therefore, her average speed is 6.7 miles per hour.

    3. Review

    4. The Meaning of Force

    5. Units of Force Force is a quantity which is measured using the standard metric unit known as the Newton. One Newton is the amount of force required to give a 1-kg mass an acceleration of 1 m/s/s. A Newton is abbreviated by a "N." To say "10.0 N" means 10.0 Newtons of force. Thus, the following unit equivalency can be stated:

    6. Direction of Force Force, like velocity and acceleration is a quantity which has both magnitude and direction. To fully describe the force acting upon an object, you must describe both the magnitude (size) and the direction. Thus, 10 Newtons is not a full description of the force acting upon an object. In contrast, 10 Newtons, downwards is a complete description of the force acting upon an object; both the magnitude (10 Newtons) and the direction (downwards) are given.

    7. Weight is a Force The force of gravity is the force with which the earth, moon, or other massive body attracts an object towards itself. By definition, this is the weight of the object. All objects upon earth experience a force of gravity which is directed "downward" towards the center of the earth.

    8. Calculating Weight The force of gravity on an object on earth is always equal to the weight of the object as given by the equation:

    9. Calculating Weight What is the weight of a student who’s mass is 50kg (110 pounds)? Weight = Fgravity = m * g Weight = Fgravity = 50 kg * 9.8 m/s2 Weight = 490 kg m/s2 = 490N

    10. Sample Problems a) The force exerted by gravity on 1 kg = 9.8 N. b) The force exerted by gravity on 5 kg = ______ N. c) The force exerted by gravity on _______ kg = 98 N. d) The force exerted by gravity on 70 kg = ________ N.

    11. Sample Problems Complete the following table showing the relationship between mass and weight.

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