PHY1: PHYSICS INTRODUCTION

PHYSICS

Definition

This deals with the study of matter in relation to energy.

Where

Matter is anything that has weight and occupies space

Energy is the ability to do work

MEASUREMENTS

The three basic quantities in physics are;

– Time

– Mass

– Length

TIME

This is a measure of the duration or period in which an event takes place e.g. speech and journey etc

INSTRUMENTS USED TO MEASURE TIME

To tell time, the following instruments can be used,

– Stop watch

– Stop clock

 

HOW TO USE THE STOP LOCK/ WATCH

– The clock must be reset to zero before using it

– Start it as the activity begins

– Stop it as the activity ends

– Read off and record the time

If different people measured the amount of time an activity takes there could be differences in the results, these differences may be due to;

1. Zero error

The hands of the clock may not get back to the zero mark on restarting.

2. Reaction time

People react to instructions at different times some may be fast and others slow.

3. Efficiency of the clock

Some clocks are not 100% efficient.

UNITS

The standard unit of time is a second [sec.]

Other units include;-

– Hours [hr]

– Minutes [min]

– Micro seconds

– Milliseconds

– Clay’s e.t.c

CONVERSIONS

1 hr = 60min

1min = 60sec

Convert the following as required;-

12hrs to;

1.mins

2. secs

Solution;

1hr = 60 min

12hrs = 60 x 12

= 720 min

-Sec

1hr = 360s

12hrs = 3600 x 12

= 43200 second

 

2. 32 min to hours

60min = 1hr

32min =  32/60

= 0.6 hours

 

1. Seconds

1 min = 60 seconds

32min = 32 x 60

= 1920 seconds

 

3. 180 seconds to hours

3600sec = 1hr

1 sec = 1/3600

180sec = 1/3600 x 180

=1/20

= 0.05hrs

1. Minutes

60 seconds = 1m

180 sec = 1/60

180 sec =1/60  x 180

= 3minutes

 

4. 36 hour to  minutes

1hr = 60min

36hrs=60×36

=2160mins.

1hr = 3600 sec

0.36hrs = 36/60 x 3600

= 1296 seconds

 

MASS

Definition

Mass is the quantity of matter contained in a substance.

The standard unit for mass is a kilogram [kg].

Other units include;-

G, mg, etc

Dg, dg,

Where

1kg = 1000g

1g = 1000mg

 

CONVERSIONS

Convert as required;-

32g to

1. mg
2. kg

1g = 1000mg

32g = 32 x 1000

= 32,000mg

2.Kg

1kg = 1000g

1g = 1/1000

32g = 1/1000 x 32

=32/1000

= 0.032kg

 

2. 002kg to mg

1kg = 1,000,000mg

0.002 =  2/1000 x 1,000,000

= 2,000mg

 

1. g

1kg = 1000g

0.002 =2/1000  x 1000

= 2 gm

 

3. 1240mg to g

1g = 1000mg

1mg =1/1000

1240mg = 1/1000 x 1240

=124/100

= 1.24gm

 

1. Kg

1kg = 1,000,000mg

1mg = 1/1,000,000 x 1240

= 124/100,000

= 0.00124kg

 

INSTRUMENTS FOR MEASURING MASS

– Beam balance

– Top pan balance

– Lever arm balance