Physics first test

Question 1

certainty

Answer 1

defined as the number of significant digits plus one uncertain ( estimated) digits-the last digit of any number is always uncertain

Question 2

exact values

Answer 2

exact values have infinite number of significant digitsIncludes:-counted values-directly counted (ex 20 students,3 dogs ,5 fingers)-defined values-always true, constant measures ( 60s/min, 1000m/km)

Question 3

what do you do with sig figs for subtracting and adding

Answer 3

you round the answer to the smallest number of decimal places of the numbers used

Question 4

base unit

Answer 4

a unit from which other units may be derived

Question 5

derived unit

Answer 5

a unit from which is derived from the base unit

Question 6

accuracy

Answer 6

-measures how lose a measurement is to the actual value-is expressed as a percent value(%)- poor accuracy results from flaws in equipment or procedure

Question 7

precision

Answer 7

precision measures repeatibility or consistency-it is expressed as the accepted value + a discrepancy- poor precision usually is caused by the experimenter

Question 8

qualitative description

Answer 8

describing with words using the 5 senses

Question 9

quantitative description

Answer 9

describing with numbersdescriptions made by counting numbers and measuring

Question 10

motion

Answer 10

is a measure of changes in position,marked by how far, how long and how fast an object travels

Question 11

scalar quantity

Answer 11

any quantity has magnitude(size)but no directionex:-distance-types of speed-speed calculations-distance-time

Question 12

vector quantity

Answer 12

a quantity that has magnitude ( a size number), and direction-direction is shown by drawing an arrow above the units symbol

Question 13

distance

Answer 13

the Greek letter “delta”,(triangle symbol), means “change in”-distance measures the total travel of an objectunits are metres(m) or kilometres

Question 14

time

Answer 14

time is the time duration between 2 events1hr=3600s

Question 15

speed

Answer 15

speed is a measure of the distance of the object per unit timeunits are m/s or km/h1m/s=3.6km/htypes of speed:1.constant speed(uniform motion)- an object travelling at the same speed of a period of timeex.cruise control,speed of light in air2.average speed-the total distance over the total timeex.a trip to St.John’s takes 6.5h in 689km3. instantaneous speed-the speed at a particular moment in time-instantaneous speed is not affected by an objects previous speed of how long it has been movingex.speedometer and police radar gun

Question 16

Graph basics

Answer 16

y axis = dependent variable,it is depedent on the x axis changesx axis= independent variable,values chosen by eperimenter-always put a title- always use a proper scale-if the points follow straight use a line of best fit -if the points follow a curved line path,draw a curved ;in of best fit(for distance time graphs)y axis = distancex-axis= time-the slope= speed the slope= the change in y ——————— the change in xspeed =distance ————- time

Question 17

In a speed time graph what does the slope equal?

& what does the area under the line represent?

Answer 17

( speed time graphs show changes in time when an object is accelerating)
- the slope of a speed/time graph equals the acceleration
(Slope a= delta v divided by delta t

If the slope is a positives it means it is increasing speed

The area under the line is equal to the distance travelled.
( the area of the rectangle equals (b)(h), area of the triangle = bh divided by two