# Unit 2: Vocabulary Words & Concepts – 803

## Vocabulary Quiz 1:

• Gravity – Force of attraction between all objects in the universe. On Earth all objects fall towards the center of Earth’s mass.
• Newton – The Newton is the basic SI unit of force.
• Weight is an example of force. An objects weight is a measure of the force of gravity acting on the object. When you weigh an object you measure the pull of gravity on the object.
• Spring scale –Measures the force of gravity on an object.
• Friction – Force that opposes the motion of an object.
• Useful Friction – makes motion possible, riding a bike.
• Harmful Friction- makes motion difficult (machine part with moving parts that touch, these parts can produce heat and can cause parts to wear out.
• Compression is the force applied when two objects are pushed together. Think of a stack of heavy stones. The force crushing down on the bottom stone is compression.
• Tension is the force applied when an object is pulled or stretched. A good example is the surface of a trampoline. When someone jumps down on the trampoline, the material stretches.
• Lubricants – materials that reduce friction such as lubricants in a car’s engine.
• Moving Against Friction – Friction makes it hard to move objects.
• Rolling Friction – reducing friction to make it easier to move objects.
• Air resistance – force that goes against (opposes) the movement of an object in air .
• Terminal velocity – speed of which air resistance and gravity acting on a falling object are equal.
• Vacuum – empty space.
• Pressure- force per unit area . Pressure = force / area
• Air pressure- pressure caused by the weight of Earth’s atmosphere.
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## Energy: Vocabulary Quiz 2:

• Potential energy – the energy stored in an object because of its position.
• Thermal energy – warmth, this energy increases as its temperature increases.
• Chemical energy – the energy stored in chemical bonds. When chemicals are broken apart and new chemicals are formed, some of this energy is released.
• Radiant energy – the energy carried by light.
• Electrical energy – energy that is carried by electrical current.
• Nuclear Energy – The energy stored in the nucleus of an atom to generate electricity. Nuclear energy can be transformed into different types of energy.
• Law of conservation of energy – energy is never created or destroyed. The only thing that changes is the form in which energy appears.
• Renewable energy – this is an energy source that is replenished continually. Example – hydroelectric power plants uses rain, snow, water from rivers to generate electrical energy.
• Alternative resources- these include solar energy, wind, and geothermal energy.
• Inexhaustible resources – this is an energy source that can’t be used up by humans, such as solar energy.
• Work – work is done when a force causes an object to move in the same direction that the force is applied.
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