Ch 1 Physical Quantities and Units

Question 1

All physical quantities consist of __________ and ___________.

Answer 1

magnitude and unit

Question 2

What are the 5 base quantities?

Answer 2

mass, length, time, current, temperature

Question 3

What is the SI unit of mass?

Answer 3

kilogram (kg)

Question 4

What is the SI unit of length?

Answer 4

meter (m)

Question 5

What is the SI unit of time?

Answer 5

second (s)

Question 6

What is the SI unit of current?

Answer 6

ampere (A)

Question 7

What is the SI unit of temperature?

Answer 7

kelvin (K)

Question 8

What is the SI unit of speed?

Answer 8

meters per second (m/s)

Question 9

What is the SI unit of acceleration?

Answer 9

meters per square second (m/s2)

Question 10

What is the SI unit of density?

Answer 10

kilogram per cubic meter (kg/m3)

Question 11

What is a scalar quantity?

Answer 11

A quantity with only magnitude.

Question 12

What is a vector quantity?

Answer 12

A quantity with both magnitude and direction.

Question 13

Convert 0.001 m to mm.

Answer 13

1 mm

Question 14

Convert 300 g to kg.

Answer 14

0.3 kg

Question 15

Convert 0.00001 m to micrometer.

Answer 15

10 micrometer

Question 16

Convert 200 000 W to MW.

Answer 16

0.2 MW

Question 17

Convert 20 000 000 J to GJ.

Answer 17

0.02 GJ

Question 18

Give one example of a vector quantity.

Answer 18

Any of the following is correct: velocity, acceleration, force, displacement, weight.

Question 19

Give one example of a scalar quantity.

Answer 19

Any of the following is correct: speed, distance, time, mass, current, voltage, resistance etc.

Question 20

Newton’s third law involves two quantities which are equal in size and opposite in direction. What is the unit for these two quantities?

Answer 20

N

Question 21

Which quantity is a scalar?

A acceleration

B force

C temperature

D velocity

Answer 21

C Temperature

Question 22

Vectors can be represented using arrows:

The direction of the arrow shows _____________

The length of the arrow represents ____________

Answer 22

Direction,magnitude

Question 23

Rulers can be used to measure small distances of a few cm. They are able to measure to the nearest

Answer 23

mm

Question 24

When measuring larger distances (of a few metres) a ___________ is more appropriate or, when measuring even larger distances, ___________

Answer 24

tape measure,Trundle wheel

Question 25

a. Measuring cylinders can be used to measure the ________ of liquids
b. The change in volume of the liquid in the cyclinder is equal to ______________.

Answer 25

a. Volume
b. Volume of irregular shaped object

Question 26

When reading the volume of the scale of measuring cyclinder, use the __________ meniscus

Answer 26

Lower/bottom

Question 27

Suppose you have to measure the thickness of a sheet of paper. The thing that you are trying to measure is so small that it would be very difficult to get an ________ answer

If, however, you measure the thickness of 100 sheets of paper you can do so much more accurately. Dividing your answer by 100 will then give an accurate figure for the thickness of one sheet

Answer 27

accurate

Question 28

This process of taking a reading of a large number of values and then dividing by the number, is a good way of getting accurate values for small figures.

Think of another example where we might use this technique.

Answer 28

the time period of a pendulum – measure the time taken for 10 (or more) swings and then divide that time by no. of swings

Question 29

Accuracy

Answer 29

a measure of how close the results of an experiment agree with the true value.

Question 30

The accuracy of a reading can be improved by _______________________

Answer 30

repeating the measurements.

Question 31

Precision

Answer 31

is a measure of how close the results of an experiment agree with each other. It is a measure of how reproducible the results are.

is how close the measured values are to each other but they may not necessarily cluster about the true value.

Question 32

High precision implies

Answer 32

a small uncertainty and small random error.

Question 33

When there is high accuracy

Answer 33

there will be small systematic error

Question 34

For accurate measurement, the eye must always be placed vertically above the mark being read. This is to avoid _________ which will give rise to inaccurate measurement.

Answer 34

Parallex error

Question 35

Parallax errors affects the accuracy of the measurement.

1. If you consistently used the incorrect angle to view the markings, your measurements will be displaced from the true values by the same amount. This is called __________.
2. However, if you used different angles to view the markings, your measurements will be displaced from the true values by different amounts. This is called ___________ .

Answer 35

1. systematic error
2. random error

Question 36

Reading the tape from ticker tape timer

Answer 36

For X, the dots are evenly spaced. Since the length is 1 m, the spacing between each dots is 0.2 m. We can calculate the speed of the object using Speed=DistanceTime=0.20.1=2m/sSpeed=DistanceTime=0.20.1=2m/s Hence, X represent the tape from an object that is moving at constant speed.

For Y, the spacing between the dots increases as time passes. Since the dots are made with a fixed time interval, the time in the formula above is fixed. We will get an increasing speed as the distance between the dots increases. Hence, Y represent the tape from an object that is accelerating.

For Z, the spacing between the dots decreases as time passes. Using the same reasoning as above, Z represent the tape from an object that is decelerating.

Question 37

1 cm = 0.01 metre

1 kg = ___________ grams

1 GB = 1 000 000 000 bytes

0.000 0052 s = _________s

Answer 37

1000, 5.2×10⁻⁶