energy conversion of energy forms of energy energy work
Post on 16-Dec-2015
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Energy
Conversion of Energy
Forms of Energy
Energy
Work
Work• The product of force and distance
moved in the direction of the force• W = F x d• Units: Newton-meter, Nm
– Equivalent to Joule, J
Work Example
• A force of 10N is applied to a box to move it 2m along the floor. What is the work done on the box?
• A bodybuilder, 1.6 m tall lifted a 30-kg mass from the ground up to his head. How much work did he do?
Which force does more work?
Energy• The ability to do work• Work ~ Energy• Units: Nm, J• May be:
– Transferred– Stored– Transformed
Forms of Energy• Kinetic Energy
– Energy due to motion– Equation:
• EK = ½ mv2
• Potential Energy– Energy due to position– Equation:
• EP = mgh
Examples• What is the kinetic energy
of a 3-kilogram ball that is rolling at 2 meters per second?
• What is the potential energy of a 3 kilogram-ball that is 3m above the ground?
Forms of Energy• Chemical Energy
– Energy due to chemical reaction
• Nuclear Energy– Energy due to nuclear
reaction
Forms of Energy• Thermal Energy
– Energy transferred due to difference in temperature
• Electrical Energy– Energy due to
movement of charges
Forms of Energy
• Light Energy
• Sound Energy
Conversion of Energy
Conversion of Energy
Is this right or wrong?
Conversion of Energy
Example 1
• A box of mass of mass 3 kg is dropped from a height of 5m. Neglecting air resistance, calculate:– The potential energy of the box before it is
dropped– The kinetic energy of the box just before it
reaches the ground– The speed of the box just before it strikes the
ground
Example 2
• A ball of mass 60 g is thrown upwards with an initial speed of 30 m/s. If air resistance is negligible, calculate:– The initial kinetic energy of the ball– The initial potential energy of the ball– The potential energy of the ball when it reaches
its greatest height– The greatest height reached by the ball
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