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Given that its SPEED DECREASES from V to v/2 after TRAVELLING =3cm
acceleration of bullet=vsquared-usquared
                                  --------------------------=a
                                       2s

We all KNOW that light travels in a straight line and mirror reflected the light BACK.so when light FALLS on a mirror they REFLECT back in a straight line.and when light falls on a wall and they have no place to get reflected back so the light LOOKS in a bigger manner.

The materials required are Cardboard,a motor , a battery, a fan, a switch and wire. 
Its very easy to make it. Cut out the cardboard sheet into three equal TRIANGULAR pieces. Fix motor with the fan in one of the triangular sheet and place all the triangular SHEETS VERTICALLY. Put the switch at the back of WINDMILL. And u are done

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It is USED  in MAKING obtical

As the bullet with velocity 150 m/s COMES to REST in 0.03 seconds, its acceleration
a = v-u / t = 0 - 150 / 0.03 = -5000 m/s^2
Therefore, distance TRAVELLED in this time
S = ut + 1/2at^2 = 150*0.03 - (1/2*5000*0.0009) = 4.5 - 2.25 = 2.25 m

The distance of penetration of the bullet into the block is 2.25 m.

Clinical THERMOMETER is used for measure the temp. of body
its RANGE is UPTO 122'C
it is used in hospital
laborotary thermometer is used for measure the temp.of any sub.
its range is very high
it is used in LABS

Sky appears BLUE due to scattering of light.blue colour have lower wavelength scatters less.scattering is due to the presence of dust particles  present in the atmosphere.sky appears red incolour  in morning and evening. at this TIME light has to travel along distance,since sun RISES in east and SETS in west.hereduring this time colours of smaller wavelengths will GET scattered off and sky appears with colours of longer wavelength ie redcolour,planet is a nonluminous body ieit doesnot have its own colour and it reflect the light of sun

Q.Magnification PRODUCED by a MIRROR 1/3 then TYPE of mirror isans Magnification produced by a mirror 1/3 then the type of mirror 1/3 NARROW

The energy TRANSFERRED from a body to another DUE to temperature DIFFERENCE b/w them is called HEAT.

1) length of slinky = 2m
time taken by WAVE = 10 sec.
4 TIMES of slinky = 2*4 = 8m
speed = distance travelled by wave/time
         = 8/10
         = 0.8 m/sec.
2)  frequency = 280 sec^-1
it MEANS it will vibrate 280 times in a second
speed of sound in air = 336m/sec.
distance travelled BU sound in air = 18cm. = 0.18m.
time taken by sound = distance/speed
                              = 0.18/336
                              = 0.00053 sec.
tuning fork take 1SEC. to vibrate 280 times
so in 0.00053 second it will vibrate 0.00053*280 times = 0.15 times

The direction of light propagation can be changed at the boundary of TWO media having DIFFERENT densities. This property is called REFRACTION

When a current-carrying conductor is placed in a MAGNETIC field, the conductor experiences a force which acts to push the conductor out of the field. This is the principle of operation of an analogue ammeter and voltmeter. 
A light coil of wire supporting a pointer is placed between the poles of a permanent magnet. Whenever the coil rotates, the pointer sweeps across an appropriately-calibrated scale. When current flows through the coil, a torque acts to rotate the coil. However, the movement of the coil is restrained by a pair of hairsprings. When the torque due to the current is balanced by the restraining torque of the hairsprings, the coil stops rotating. Thus, the angle through which the coil rotates is proportional to the current FLOWING through it, and the instrument is calibrated such that the pointer directly indicates that value current on a curved scale.

Ammeters and voltmeters both work on the same principle. In the case of the voltmeter, the current which OPERATES the coil is proportional to the voltage appearing across the instrument. The difference between the two instruments is the WAY in which resistors are used, within the instruments, to make one suitable for measuring current and the other suitable for measuring voltage.

Ammeters must be connected in series with the circuit under test, whereas voltmeters must be connected in parallel with the circuit under test.

Digital ammeters and voltmeters work on a completely different principle, using an electronic 'gate' to switch on and to switch off a series of pulses. The time for which the gate is 'open' is a function of the value of the current or voltage being measured -e.g. the larger the current, the LONGER the gate is held open. These pulses are then counted and, in simple terms, the greater the number of pulses counted, the greater the current or voltage being measured. The output is then presented, directly in amperes or volts, on a LED or LCD screen. 

Mass of each BULLET (m) = 50g = 0.05kg
number of BULLETS per MINUTE (n) = 216
time(t) = 60s
velocity (v) = 1000 m/s
Let the force required to HOLD the gun = F

Force×time = momentum
⇒ F × t = n × mv
⇒ F × 60s = 216 × 0.05×1000
⇒ 60F = 10800
⇒F = 10800/60 = 180N

Force required to hold the gun is 180N.

In a regular wave :  speed of the wave = Frequency * WAVELENGTH

1)   
     Frequency = c / wavelength = 3 * 10⁸ / 25 = 1.20 * 10⁷  Hertz

2)
   the minimum separation = wavelength = 48 m/s  /  12 HZ  =  4 meters.

The ROOM temperature = 5 ⁰C

The air in the room and the walls and other objects will be heated up TAKING the heat from the hot WATER in the tank.  The temperature of the water in the tank COMES down to 5°C.

   heat liberated =  mass * specific heat capacity * temperature difference
                       = 0.5 m³ * 1000 kg/m³  * 4.18 kJ/°C/kg  * (20° - 5°C)
                   = 31, 350 kJ

Do ECOFRIENDLY plastic with MILK. 
process: take some milk in a bowl and ADDS some vinegar to it. after some time  you can OBSERVE the clumps formed by milk. take out that clumps and take out the water in that clumps and make it dry. then it will be act as a plastic

If we WANT to FIND the displacement of a body we can SUBTRACT its INITIAL POSITION vector from its final position vector.

1)Sound is the FORM of energy that creates the sensation of hearing.2) See the images below.3)BELL jar experiment4)Sound waves in air (and any fluid MEDIUM) are longitudinal waves because particles of the medium through which the sound is transported VIBRATE parallel to the DIRECTION that the sound wave moves.

In LENS with CENTRE as O, the IMAGE will FORM between F‚ and 2F‚ . In lens with centre as O' , the image will form at INFINITY.

1. EVAPORATION takes PLACE at all temperatures, while boiling occurs at a PARTICULAR temperature.
2. Evaporation takes place from the surface, WHEREAS the entire liquid boils.
3. Evaporation can occur using the INTERNAL energy of the system, while boiling requires an external source of heat.
4. Evaporation produces cooling but boiling does not.
5. Evaporation is a slow process while boiling is a rapid process.

hopi i helped you.... 

When dog KEEP its tongue out during hot summer days,the process of evaporation TAKES PLACE i.e., the saliva which is present on the tongue of the dog evaporate as VAPOUR and it FEELS a cool sensation.so,dogs pant during hot summer days.

F = -10 cm
m = 4 = -v/u
v = -4u
u = ?
1/f = 1/v + 1/u
-1/10 = -1/4u + 1/u 
on solviing this u can find the value of u, i.e object distance
the ANS. is -7.5 c.m

A = v/t 
THEREFORE, a = 25 / TIME

Their SIZES and the DISTANCE between PLANETS and each of them

When a solid is PUT on the surface of water (or a LIQUID), the weight of water that is displaced (= volume of solid that is below water surface) is the buoyancy force ACTING upwards on the solid.

A needle MADE of iron has DENSITY higher than water.  It displaces as much water as its volume.  The weight of water so displaced is much less than weight of the needle.
A ship is made of iron as well as many other materials.  It contains a lot of free space filled with air (open).  It displaces a lot of water as its bottom is quite wide.  The weight of water so displaced is quite high and equal to the weight of water.  So  the ship floats on the surface.  The ship is manufactured to have such a base.

It is because of buoyancy FORCE of WATER which MAKE the OBJECT to PUSH up