7f6e573239cd54ea1018258f71e0603f.ppt

- Количество слайдов: 41

Scientific Method 6 Basic Steps • 1) State the _____ • 2) Gather information • 3) Form a _______ (educated guess) • 4) Test the hypothesis (____) • 5) Analyze ______ • 6) Draw ____

Variable - quantity that can have more than ____ • dependent variable - value changes according to the ____ in the other variables (ex. _____) • Variable you ____ to see how it will affect the ______ variable is called the independent variable (ex. Time)

Terms • Control – standard by which test results are _______ • Constant – factor that ______ change in an experiment • Theory – explanation based on knowledge from many _____ & _____ • _____ – statement about what happens in nature (ex. Gravity)

Graph – visual display of _____ • _____ types – – – Line Bar Circle or pie

Line graph • Dependent _______ plotted on y axis • Independent variable _______ on x axis • Always _______ your graph • Label both the x & y ______ • Use a _____ when drawing a graph • Make graph large enough to cover ______ ¾ of the space provided

SI – international system of _______

SI Prefixes • Based on multiples of • _______ units – – – Gram (__) ______ (l) Meter (__)

Base units • Meter – measures • • ____ Liter – measures ____ Gram – measures _____

Density – mass per unit ______ • Mass - measurement of the ____ of matter in an object • A bowling ball has a ____ of about 5, 000 g • roughly 100 times greater than _____ of a golf ball & 2, 000 times greater than a table-tennis ball’s mass

Amount of ______ occupied by an object - volume • To find volume of a ______ (such as a brick) • Measure its length, _______, & height • Then multiply the ____ numbers & their units together ( V = 1 x w x h) • (For a brick) measurements probably would be in centimeters • Volume would be ____ in cubic centimeters, cm 3

Water Displacement Method – used to find ______ of irregular solid • 1) put _____ in graduated cylinder • 2) ______ initial amount of water • 3) gently add “irregular solid” ex. _____ • 4) Record final ______ level • 5) ______ the water levels to determine volume of the solid • 6) volume will be expressed in _____ (ml)

Sample Problems – Volume • 1) Each side of a cube is 2. 8 cm, what is the volume of cube? • 2) What is volume of a box that is 18. 9 cm long, 9. 2 cm wide, and 3. 1 cm high? • 3) With 12. 6 ml of water in a graduated cylinder, a rock is added and the water level rises to 18. 3 ml. What is the volume of the rock?

Density = mass/volume • 1) What is the density of a box with a mass of 3 176 g and a volume of 3. 2 cm 3? • 2) What is the volume of a liquid with a density of 18. 6 g/ml and a mass of 96 g? • 3) What is the mass of an object that has a 3 density of 12. 4 g/cm 3 and a volume of 4. 31 cm 3?

Speed & Velocity • Frame of ______ – needed to determine _____ • of object ex. Sign post Distance – change in _____ – SI unit – _______ (m) – How far it has moved • Speed – distance an object _____ per unit of time – Speed = distance/_______ – SI ___ – meter/second (m/s) or larger unit (km/h)

Speed S=d/t • 1) A car traveling at a constant speed covers a distance of 750 m in 25 s. What is the speed? • 2) A passenger elevator operates at an average speed of 8 m/s. If the 60 th floor is 219 m above the 1 st floor, how long does it take the elevator to go from the 1 st to 60 th floor?

S = d/t • 3) A motorcyclist travels an average speed of 20 km/h. If the cyclist is going to a friend’s house 5 km away, how long does it take the cyclist to make the trip? • 4) An ant travels 75 cm in 5 s. What was the ant’s speed? • 5) It took you 6. 5 h to drive 550 km. What was your speed?

Average Speed

Average speed • total distance traveled • _____ by the total time of travel total distance traveled was 5 km and the total time was 1/4 h, or 0. 25 h. The average speed was _______

Instantaneous Speed • speed at a given ____ • • • in time Ex. Speedometer speeding up or slowing down – _______ speed is changing _______ speed, the instantaneous speed _______ change

Displacement • _____ & ______ of an object's change in position from the starting point • length of the runner's displacement & the distance traveled would be the _____ if the runner's motion was in a single direction

Motion • ______ of an object • • over a period of time can be shown on a distance-time graph Time – plotted on ____ axis Distance traveled – plotted on vertical ___

Graphing Motion

Velocity = distance/____ • speed of an object & • • the _____ of its motion velocity of an object ____ even if the speed of the object remains constant SI unit – ______ Change in speed = change in _____ as long as direction remains the _____

______ • Rate of change in _______ • Occurs when object changes ______, direction, or BOTH • _______ acceleration – speed increasing • Negative acceleration – speed _____

Positive Acceleration • acceleration is in the same ______ as the velocity – speed increases

Negative Acceleration • speed _______ – the acceleration is in the ______ direction from the velocity

Changing Direction • speed of the horses in this carousel is _____, but the horses are accelerating because their direction is _______ constantly

Calculating Acceleration

Calculating Velocity

Sample Problems • 1) A jet starts at rest and at the end of runway it has reached a speed of 80 m/s in 20 s. • 2) Skateboarder moving in a straight line at a constant speed of 3 m/s and comes to stop in 2 s.

_____ – push or ____ • Sometimes ______ • • forces are obvious but not always can cause the ______ of an object to change force of moving ball causes ball at rest to move in the _______ of the force

Forces • ___ force – 2 or more • • forces acting on a object @ same ____ zero because the ___ forces cancel each other Forces ____ in size & _______ in direction – balanced forces

____ forces • 2 students pushing with • ____ forces in opposite directions – net force occurs in the direction of the _______ force net force – will be the _____ between the two forces because they are in opposite ____

Unbalanced forces • forces are combined • (______ together) because they are exerted on the box in the _______ direction net force that acts on this box – found by _______ the two forces together

Inertia – tendency of an object to _______ any change in its motion • If object is _______, it will have uniform motion • It will keep moving at the same _____ & in same ____ unless acted on by an unbalanced force • velocity of the object remains _______ unless a force changes it • object at ______ remains at rest

Inertia • inertia of an object is related to its mass – greater the ____ of object the greater its inertia • Sir Isaac ______ – stated rules that describe the effects of forces on the _______ of objects – known as Newton's law's of motion

Newton’s ______ Law of Motion • Also called the law of _______ • states that an object moving at a constant velocity keeps moving at that _______ unless acted on by an unbalanced net force • object at rest stays at ____ unless acted on by an unbalanced net force

law of inertia – explains what happens in a car crash • A car traveling about 50 km/h collides head -on with something solid, the car crumples, slows down, and stops in about 0. 1 s

law of inertia – explains what happens in a car crash • Any passenger not wearing a safety belt continues to move _______ at the same speed the car was traveling • Within about 0. 02 s after the car stops, unbelted passengers slam into the dashboard, steering wheel, windshield, or the backs of the front seats

law of inertia – explains what happens in a car crash • force needed to slow a person from 50 km/h to zero in 0. 1 s is equal to 14 times the force that gravity exerts on the person • belt loosens a little as it restrains the person, increasing the time it takes to slow the person down • this reduces force exerted on the person • safety belt also prevents the person from being thrown out of the car