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Spring stretched due to act of it gravitational force. Let if mass of spring is m then Fg = mg° ( weight ) e.g Fs = Fg Kx = mg° ----------(1)

But we know, g is varies with height from earth surface. e.g g = g°/( 1 + h/r)²

where h is height from the surface of earth . at h = 800 km , and r = 6400 km

g =g°/( 1+ 800/6400)² =g°/( 1 + 1/8)² =g°/(9/8)² =64g°/81

Now, spring stretched act by gravitational force = m64g°/81 F"s = F"gKx" = 64mg°/81 --------(2)

equation (1) and (2)

x/x" = 1/(64/81)

x" = 64x/81 hence 64/81 times stretched spring at h = 800 km

e.g stretching of spring = 64×1/81 cm= 64/81 cm

the net acceleration is g+a = 10+5 = 15m/s²

so, Initial thrust is mass*(net acceleration) = 20,000*(15) = 3×10^5 N

what is the acceleration of one of the balls.

Option D

Conservation of linear momentum in the direction perpendicular to the initial velocity : m v1 sin 60° - m v2 sin 60° = 0 v1 = v2

conservation of linear momentum in the direction of initial velocity of the first ball: m u =m v1 cos 30° + m v2 cos 30° 9 = 2 v cos 30 = 2√3 v

v = 3√3 /2 m/s = 2.6 m/s

v²=u²+2as here in both case u will be zero

momentum(p)=velocity × mass

here we need v

v=√2as (a=g=10m/s²)

in first case v = √2×10×4 =4√5

p = 4√5 × 3

= 12√5in case 2

v=√2×10×9

= 6√5

p= 6√5 × 2

=12√5HENCE RATIO IS 1:1

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Physical quantities are the substances which can be measured. By measuring physical quantities, we can measure the mass, weight and other physical properties.So, standard measuring unit should be there for measuring physical quantity

The SI unit of electric field strength is newtons per coulomb (N/C) or volts per meter (V/m). The force experienced by a very small test charge q placed in a field E in a vacuum is given by E = F/q, where F is the force experienced.

The SI unit of electric field strength is Newton per Coulomb (N/C) or volts per meter (V/m) .The force experienced by a very small test charged q placed in a field E in a vacuum is given by E = F/qwhere F is the force experienced.

The Cl- ions diffuse to the surface and form LiCl with {Li}^{+} ions. An electron is released which diffuses into the crystal and occupies the anionic site. Such anionic sites occupied with electrons are called F-centres. These impart pink colour to the crystal. The colour results by the excitation of the electrons on absorbsing energy from visible light falling on the crystals

electric field due to +e charge will be outward.. and due to -e charge will be inward adding up to 0

so, flux ∅ = 0

thermos flask

Running the refrigerator makes the room warmer and if you leave the door open, the room warms up even faster. The first rush of cold air may cool things down a little, but in the long run, the room will get warmer.

To see why, we need to think of heat as energy and cold as a lack of energy. But the refrigerator can’t actually produce cold. All the refrigerator does is move heat, or energy, from one place to another. As the food inside the refrigerator loses its heat–or, in other words, gets colder–thatheat ends up in the room.

Periodic motion exceuted by a swing machin

Galilean transformationis used to transform between the coordinates of tworeference frameswhich differ only by constant relative motion within the constructs ofNewtonian physics. These transformations together with spatial rotations and translations in space and time form theinhomogeneous Galilean group(assumed throughout below). Without the translations in space and time the group is thehomogeneous Galilean group.

After the nuclear war, the clouds caused might cover most parts of the sky, there by preventing solar light to reach most parts of the globe .

This would result in a winter.

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Light as a wave:Light can be described (modeled) as an electromagnetic wave. In this model, a changing electric field creates a changing magnetic field. This changing magnetic field then creates a changing electric field and BOOM - you have light. Unlike many other waves (sound, water waves, waves in a football stadium), light does not need a medium to “wave” in.

Light as a particle:The textbook might start off with some experimental evidence from the historic photoelectric effect to show that the wave model of light doesn’t always describe what happens.

what is R here

R is the radius of path of the two particles.

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He should keep the object within focus to obtain a clear, virtual and erect image.

He should keep the object within focus to obtain a clear, virtual and erect image.

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