Review Notes #10 Motion and Energy

Forces A force is either push or pull. Can stop an object, change its speed or cause it to change directions. Exs. Balanced(top picture) and Unbalanced (bottom Picture) forces

Gravity All objects pull on other objects. The amount of pull depends on mass and distance. Large masses close together have a large gravitational force.

Motion Velocity is how fast an object is moving and in which direction. Also the change in distance over a certain time Acceleration is how fast an object speeds up or slows down. Slowing down is negative acceleration. Change in Velocity over a certain time.

Newton’s Laws 1st law – Law of inertia. An object in motion stays in motion, object at rest stays at rest unless acted on by an outside force. 2nd law – F = ma 3rd law – For every action, there is an equal and opposite reaction.

Work and Machines Work – a force moves an object a distance. A machine can do work. A machine puts in effort force to overcome resistance force. No machine is 100% efficient. Simple Machines – screw, lever, pulley, inclined plane, wheel and axle, wedge.

Energy Energy is the ability to do work. Potential energy is stored. A certain height. Kinetic energy is energy because an object is moving. Energy can’t be created or destroyed only change forms. Mechanical, sound, chemical, electrical, nuclear, light, heat.

Waves Light and sound travel in waves. Longitudinal waves push and pull. Transverse waves go up and down, High amplitude, large volume High frequency, high pitch.

Sound Produced by a vibrating object. Doppler effect is what you hear when an object approaches and passes you. The denser the medium the faster sound travels. Temperature can also influence speed of sound.

Heat The vibrating motion of molecules. Increase heat, molecules speed up and spread out. Conduction – transfer by touch Convections – transfer by warm rising and cool sinking Radiation – transfer by waves through space.

Magnetism Magnets have north and south poles. Poles are where the magnets are strongest. Opposite poles attract. Similar poles repel

Electricity Like charges repel and opposites attract. Conductors, let electricity pass Insulators prevent electricity from flowing. Circuits – Need energy source, path, and energy user. Series – one goes out they all go out, add one user and the rest get dimmer. Parallel – wired like your house.

Light Light travels in straight paths called rays. Light is 1,000,000 times faster than sound. Light can be absorbed, reflected, or transmitted. Light can be bent or refracted.

Electromagnetic Waves Light can travel through a vacuum in the form of electromagnetic waves. Include x rays, radio waves, and other things we see in every day life.