PHYSICS [1 Mark Question Answer]

We will use a measuring tape to measure the perimeter of our playground.
To measure the length of the playground the tape is spread along the length of the curved area.

1 yard = 0.91 m

1ft = 30.48cm

l2 inch 1 ft

In our daily life, we measure the following four basic physical quantities.

1. Length
2. Mass
3. Time
4. Temperature

The S.I. unit of area is a square metre or meter2 which in short form is written as m2.

The total surface occupied by an object is called its area or surface area.

The temperature is boiling water = 100 °C.

The temperature is melting ice = 0 °C.

Two characteristics of a unit are:

1. It should be of convenient size.
2. It must be universally accepted, i. e. its value must remain the same at all places and at all times.

Common unit of temperature is degree centigrade (symbol °C)

The S.I. unit of temperature is Kelvin (symbol K).

Temperature measures the degree of coldness and hotness of a body.

3 minute = 15 second
1 minute = 60 second
3 minutes 15 second = 60 × 3 + 15
= 180 + 15
= 195 seconds

Two devices used to measure the time interval of an event are

1. StopWatch
2. Stop Clock

The mass of 1 litre of water at 4 °C is taken as 1 kilogram
1 quintal = 100 kg
1 metric ton = 10 quintal = 1000 kg

Measurement is a comparison of an unknown quantity with a known fixed quantity of the same kind.
The value obtained on measuring a quantity is called its magnitude. The magnitude of a quantity is expressed as numbers in its unit.

Body temperature on Monday = 102°F
Body temperature on Tuesday = 104°F
Rise in temperature = 104 — 102°F 2°F

An aeroplane leaves Bengaluru at 11:50 p.m.
and reaches Chennai at 12:40 a.m.
Duration of the flight =50 minutes

8000 g
= 80000 ÷ 1000 kg .............[As 1000 g = 1 kg]
= 8 kg

6 l
= 6 × 1000 ml ..........[As 1 l = 1000 ml]
= 6000 ml

2.25 m
= 2.25 × 100 CM ............[As 1 m = 100 cm]
= 225 cm

Measuring units are standardized so that accurate measurements can be done and are accepted universally.

We need to measure the quantities of most of the things around us to be able to take correct decisions regarding their utility. To find the exactness of an unknown quantity, we need its measurement.

Body parts have different sizes from person to person and hence the value varies. Since there is no uniformity or accuracy in the reading, body parts should not be used for the correct measurement of an object.

millilitre (mL) is the most suitable unit for measuring the volume

millilitre (mL) is the most suitable unit for measuring the volume of a glass filled with water.

The maximum volume of a liquid that a container can hold is known as its capacity. Capacity has the same units – litres (L) and millilitres (mL).

The total space occupied by an object is called its volume. volume have the same units – litres (L) and millilitres (mL).

1. The base of the measuring container can be bend inwards by hammering which reduces the capacity of liquid it can hold.
2. Some lead can be poured into the measuring container.

The bulb in a thermometer is filled with mercury. When the bulb is heated, mercury in the bulb expands and rises up in the capillary tube. The height of the mercury gives the reading of temperature.

A slight bend or kink in the capillary tube of the clinical thermometer near the bulb ensures that the mercury does not move back into the bulb when the thermometer is taken out of a person’s mouth for reading.

Mean solar day is the time taken by the earth to make one complete rotation about its own axis.

When a body to be weighed is attached to the hook, the coil is stretched downwards. The distance through which the spring gets stretched is measured by a pointer and a graduated scale attached to the spring. The reading on the scale gives the weight of the object.

The error that can arise due to the wrong positioning of the eye while reading a scale is called parallax error.

42° C or 108° F

5.50 a.m.

Stopwatch.

Second (unit of time)

The amount of matter present in an object is called it's mass. Instruments used to measure mass are beam balance, spring balance, physical balance, electronic weighing machines, etc.

Centimetre. Because a notebook has a length for which metre would be too large a unit to measure and millimetre would be too small.