Lesson one

1- Ability to do work.

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2- Energy stored in the object due to a work done on the object. [----------------------------]

3- Work done during the motion of an object.

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4- The sum of potential and kinetic energies.

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5- The stored energy in a car toy. [----------------------------]

Q. 2: Give reason for each of the following:

1- When the falling object reaches the ground, its mechanical energy equals the kinetic energy only.

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2- When the launched object reaches the maximum high, its mechanical energy equals the potential energy only.

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3- Potential energy increases as weight of object in increased.

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4- Potential energy increases by the increase of height at which the object reaches.

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Q. 3: Solve the following problems:

1- Calculate the potential energy of an object with weight = 2N at a height = 3m. from the earth's surface.

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2- What is the kinetic energy of a 5 kg. body moves with 3m/s peed.

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3- A friend launched your ball upward and vertically with 3m/s speed, at a 5m. height Determine the work done on the ball if you knew that its weight = 4 N with kg mass.

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Q. 4: Tick (P) or (x) in front of the following statements:

1- Mechanical energy equals the sum of kinetic and light energy. ( )

2- Chemical energy is stored in the stretched spring. ( )

3- The mechanical energy for the falling object on earth's surface equals the kinetic energy only. ( )

4- Kinetic energy is inversely proportional with its speed. ( )

5- Kinetic energy is directly proportional with its mass. ( )

6- During the falling of object downwards, its potential energy decreases and its kinetic increases. ( )

7- During raising a ball, its potential increases and its kinetic decreases. ( )

Q.5: Complete:

1- Potential energy = -------------- x ----------------

2- Kinetic energy = -------------- x ----------------

3- Weight = -------------- x ----------------

4- Factors affecting kinetic energy are ---------------------, ---------------------

5- Factors affecting potential energy are ---------------------, -------------------

6- Mechanical energy is the sum of ---------------------, ------------------------