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2nd Semester Review
| Question | Answer |
|---|---|
| An airplane flies past a bird. What is the reference point? | The bird...the plane is faster so it MOVES past the bed |
| 2 factors that determine speed | distance and time |
| Difference between speed and velocity | direction |
| Example of a balanced force | Picture hanging on a wall |
| DIFFERENCE between a force and work | You can apply a force without causing an object to move...WORK requires that the object moves. |
| What does an unbalanced force cause? | Change in speed and/or direction |
| Friction | opposes motion |
| Increases Friction | Sand on ice |
| Decreases Friction | Oil |
| Law of Universal Gravitation | ALL matter has mass and ALL mass is affected by gravity |
| Relationship between mass, distance, and gravity | As mass increases, gravity increases. As distance increases, gravity decreases |
| weight | measure of gravitational force |
| weight | is NOT constant |
| weight | measured in Newtons |
| Net Force | Combination of all forces acting on an object |
| Acceleration due to gravity | All falling objects accelerate towards the earth at 9.8 m/s/s |
| Freefall | The only force acting on an object is gravity |
| Freefall | makes an astronaut appear weightless |
| momentum | depends on mass and velocity |
| Bumper cars collide. The momentum of the faster car... | decreases as the velocity of the slower car increases |
| Newton's 1st Law | A moving object that is not acted on will continue moving |
| Newton's 1st Law | An object at rest will remain at rest |
| Projectile Motion | Combination of horizontal force and vertical force |
| A dart's vertical force is a result of... | gravity |
| A dart's horizontal force is a result of... | the person throwing it |
| When playing darts, aim high because of... | projectile motion |
| When you swim and push against the wall of the pool, this is an example of... | Newton's 3rd Law |
| Work output | Work done on an object by a machine |
| Work input | Work done by you on a machine |
| mechanical efficiency | comparison of work output to work input |
| Work done on an object depends on ... | force applied and distance the object moved |
| How does a ramp make work easier | By increasing the distance and decreasing the force you have to apply |
| Formula for work | Force x distance |
| What is mechanical advantage? | Force output (force the machine applies) / Force input (force you apply to the machine) |
| You apply 10 N of force to a wheel barrow. the wheel barrow applies 50 N of force to a boulder. What is the Mechanical Advantage of the wheel barrow? | MA=WO/WI MA=50N/10N MA=5 |
| Difference between a fixed and moveable pulley. | Fixed pulley only changes direction of the force...mechanical advantage is always 1 |
| Material that allows charges to move easily | Conductor |
| Material that does not allow charges to flow easily | Insulator |
| Loss of static electricity and charges move off of it | electric discharge |
| Part of a cell where charges enter and exit | electrode |
| Relationship between resistance and current | As the resistance decreases, the current increases |
| 3 basic parts of a circuit | power source, wire, load |
| Good conductors have low... | resistance |
| Circuit that provides only one path to the energy source | Series Circuit |
| electric current is made from a ... | changing magnetic field |
| This can demagnetize a magnet. | high temperatures |
| A coil of wires with an electric current | Solenoid |
| Magnets are strongest at the.... | poles |