Answer:
Explanation:
When the rock is immersed in unknown liquid the forces that act on it are shown as under
1) Tension T by the string
2) Weight W of the rock
3) Force of buoyancy due to displaced liquid B
For equilibrium we have 
=
When the rock is suspended in air for equilibrium we have
When the rock is suspended in water for equilibrium we have
+ 
=
Using the given values of tension and solving α,β,γ simultaneously for 
we get
Solving for density of liquid we get
Answer:
t = 0.28 seconds
Explanation:
Given that,
Force acting on a firework, F = 700 N
The momentum of the firework, p =200 kg-m/s
We need to find the time before it explodes. Ket the time be t. We know that, the rate of change of momentum is equal to external frce. So,
So, the required time is equal to 0.28 seconds.
Answer: Option (B) is correct.
The first law of thermodynamics is an adaptation of the law of conservation of energy, this is thoroughly adapted for the systems(thermodynamics). Law of conservation of energy defines that the total energy of a confined system is stable; energy can be transferred or converted from one form to another, but it cannot be formed or destroyed.
Answer: That is to say, a satellite is an object upon which the only force is gravity. Once launched into orbit, the only force governing the motion of a satellite is the force of gravity. Newton was the first to theorize that a projectile launched with sufficient speed would actually orbit the earth.
Explanation: Because Earth-orbiting objects follow elliptical paths around Earth and not a straight line, forces cannot, by definition, be balanced. Force is directional. It is a push or a pull in a particular direction.
A lunar eclipse occurs when the Moon passes directly behind Earth and into its shadow. This can occur only when the Sun, Earth, and the Moon are aligned (in syzygy) exactly or very closely so, with the planet in between. Hence, a lunar eclipse can occur only on the night of a full moon. The type and length of an eclipse depend on the Moon's proximity to either node of its orbit.
During a total lunar eclipse, Earth completely blocks direct sunlight from reaching the Moon. The only light reflected from the lunar surface has been refracted by Earth's atmosphere. This light appears reddish for the same reason that a sunset or sunrise does: the Rayleigh scattering of bluer light. Due to this reddish color, a totally eclipsed Moon is sometimes called a blood moon.
