General Q&A for Class 12 · Page 202
5,215 free answers in General for Class 12 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- GeneralClass 12All
Can gravity be artificially created?
True gravity cannot be artificially created, but artificial gravity effects can be simulated through centrifugal force (rotating spacecraft or facilities) and linear acceleration (constant thrust). Rotating a spacecraft creates centrifugal force that pushes occupants outward against the hull, mimicking gravity's effect. A constantly accelerating spacecraft (at 9.8 m/s²) would produce 1g of artificial gravity. However, these simulate gravity's effects without creating actual gravitational
- GeneralClass 12All
Is space 100% empty?
No, space is not 100% empty. Even in the "emptiest" regions between galaxies, there's approximately one atom per cubic meter. Space also contains: cosmic microwave background radiation, neutrinos, dark matter, gravitational waves, magnetic fields, and virtual particles that briefly pop into existence due to uantum fluctuations. Interstellar space within galaxies contains more matter gas, dust, and stellar winds. Perfect vacuum (absolute emptiness) doesn't exist anywhere in the universe.
- GeneralClass 12All
What is the speed of gravity?
Gravity travels at the speed of light: approximately 299,792,458 meters per second (about 300,000 km/s or 186,000 miles/s). This was confirmed by observations of gravitational waves from colliding black holes and neutron stars. If the Sun suddenly disappeared, Earth would continue orbiting for about 8 minutes (the time light takes to reach Earth) before the change in gravitational field reached us. This speed limit is a fundamental constant of the universe predicted by Einstein's general rela
- GeneralClass 12All
What is hidden on Earth?
This uestion is ambiguous, but several things are "hidden" beneath Earth's surface: Earth's core (solid inner core and liuid outer core of iron-nickel), Earth's mantle (dense rock layer), underground oceans (water trapped in rock minerals, possibly containing more water than surface oceans), undiscovered species (in caves and deep ocean), mineral deposits, ancient ruins and fossils, tectonic plate boundaries, and geothermal energy sources. About 99% of Earth's living space (by volume) is ocea
- GeneralClass 12All
Do you feel pain in zero gravity?
Zero gravity itself doesn't cause pain, but adaptation can be uncomfortable. Initial symptoms of space adaptation syndrome (space sickness) include nausea, headaches, and disorientation, affecting 40-50% of astronauts initially. Fluid redistribution causes facial puffiness and congestion ("puffy face syndrome"). Long-term effects include bone demineralization and muscle atrophy, which can cause discomfort. Existing injuries might feel different without gravity pulling on them. Most astronauts
- GeneralClass 12All
Why is 95% of the universe invisible?
Approximately 95% of the universe consists of dark matter (27%) and dark energy (68%), neither of which emits, absorbs, or reflects light, making them invisible. Only 5% is ordinary matter (atoms, stars, planets, us). Dark matter reveals itself only through gravitational effects, while dark energy drives the universe's accelerating expansion. These invisible components are inferred from their effects on visible matter and space itself galaxy rotation, gravitational lensing, and cosmic expansi
- GeneralClass 12All
What gravity can humans survive?
Humans can survive approximately 0.3g to 2g for extended periods, with 1g being optimal since we evolved here. Moon gravity (0.16g) would cause bone/muscle loss over time. Mars gravity (0.38g) might be sustainable with exercise. Above 2g causes severe cardiovascular strain. Brief exposures can handle more: trained pilots withstand 9g for seconds, and crash survivors have withstood over 100g for milliseconds. The direction matters too—horizontal g-forces are more tolerable than vertical.
- GeneralClass 12All
What is 84.6 minutes in gravitation?
84.6 minutes is the orbital period of a satellite orbiting Earth at its lowest stable altitude (approximately 160-200 km above sea level). This is derived from Kepler's Third Law and represents the shortest possible orbital period around Earth before atmospheric drag becomes significant. Satellites lower than this altitude experience too much atmospheric resistance and uickly deorbit. The exact period depends on altitude, Earth's mass, and gravitational constant.
- GeneralClass 12All
How is 1 hour 7 years in space?
This refers to extreme time dilation near a massive gravitational source, as depicted in the movie "Interstellar" where the characters visit a planet orbiting a black hole. According to Einstein's general relativity, time passes slower in stronger gravitational fields. Near a supermassive black hole's event horizon, gravitational time dilation can be so extreme that 1 hour locally euals 7 years for distant observers. This effect is real but reuires extraordinarily strong gravitational fields
- GeneralClass 12All
Is dark matter 100% real?
Dark matter's existence is strongly supported by overwhelming evidence, though it hasn't been directly detected. Evidence includes: galaxy rotation curves (stars orbit too fast for visible matter alone), gravitational lensing (light bending around invisible mass), cosmic microwave background patterns, and large-scale structure formation. About 27% of the universe is dark matter, compared to 5% ordinary matter. While scientists haven't isolated dark matter particles, alternative explanations w
- GeneralClass 12All
What if we lost gravity for 5 seconds?
If gravity disappeared for 5 seconds, everything not anchored down would float upward at Earth's rotational velocity (1,670 km/h at the euator). The atmosphere would begin dispersing into space, oceans would lift off coastlines, and objects would continue along their current motion vectors. When gravity returned, everything would crash back down simultaneously, causing catastrophic destruction. However, this scenario is physically impossible gravity can't simply "turn off" as it's a fundament
- GeneralClass 12All
What would happen if gravity disappeared for 5 seconds?
If gravity vanished for 5 seconds: You'd float upward at Earth's rotation speed (up to 1,670 km/h at euator). The atmosphere would begin expanding into space. Oceans would lift from their basins. Satellites would drift from orbits. The Moon would begin moving away in a straight line. When gravity returned, everything would crash down simultaneously, likely causing extinction-level destruction. Fortunately, this is impossible gra
- GeneralClass 12All
Will we lose a second in 2029?
This refers to potential "leap second" adjustments in timekeeping. Earth's rotation is gradually slowing due to tidal friction with the Moon, reuiring occasional one-second adjustments to keep atomic clocks synchronized with Earth's rotation. However, in November 2022, authorities voted to eliminate leap seconds by 2035, so the 2029 adjustment may not happen. The concern isn't "losing" time but coordinating our precise timekeeping systems with Earth's irregular rotation.
- GeneralClass 12All
Can we live on Earth without gravity?
No, life as we know it cannot exist without gravity. Gravity is essential for: planetary formation (without it, matter wouldn't coalesce into planets), atmospheric retention (gases would escape to space), water distribution (oceans and rivers depend on gravity), biological processes (blood circulation, digestion, bone/muscle development), orbital mechanics (Earth wouldn't orbit the Sun), and star formation (gravity creates the pressure for nuclear fusion). The entire structure of our universe
- GeneralClass 12All
Can a human survive 10 times gravity?
Humans cannot survive sustained 10g forces. Even brief exposures cause severe physiological effects: immediate loss of consciousness due to blood pooling away from the brain, potential heart failure, crushed organs, broken bones, and respiratory failure (chest too heavy to expand). While race car drivers have survived brief (millisecond) impacts exceeding 100g with proper safety euipment and body positioning, sustained 10g for more than seconds would be fatal for anyone without extraordinary
- GeneralClass 12All
Can humans survive 2 times gravity?
Yes, humans can survive and adapt to 2g (double Earth's gravity), though it would be extremely challenging. Short-term exposure causes discomfort, fatigue, and difficulty breathing and moving. Long-term adaptation might be possible with training, but would cause cardiovascular strain (heart working twice as hard), bone and muscle stress, circulation problems, and reduced mobility. People with heart conditions or elderly individuals would struggle severely. Athletic activities would be nearly
- GeneralClass 12All
What is the 1.3 seconds that vanished?
This likely refers to various phenomena: Accumulated leap seconds (about 27 seconds added since 1972 due to Earth's slowing rotation). Time lost during high-precision GPS corrections. Relativistic time differences between Earth and satellites (GPS satellites run 38 microseconds fast per day due to weaker gravity, reuiring constant correction). Possible confusion with time dilation effects. Without specific context, this uestion is difficult to answ
- GeneralClass 12All
What is g 9.8 called?
g = 9.8 m/s² is called "standard gravity," "gravitational acceleration," or "acceleration due to gravity" on Earth. The symbol "g" (lowercase) specifically represents this acceleration value. It's sometimes called "standard Earth gravity" or simply "gravity constant" (though this can be confused with G, the gravitational constant). In scientific notation, it's often written as 9.80665 m/s² for precise calculations.
- GeneralClass 12All
What is the force of gravity?
The force of gravity is the attractive force between any two objects with mass. On Earth's surface, it's calculated as F = m × g, where m is mass and g is 9.8 m/s². For any two objects in space, it's F = G × (m₁ × m₂) / r². Gravity gives objects weight, keeps planets in orbit, holds galaxies together, and is responsible for the large-scale structure of the universe. Unlike other forces, gravity is always attractive and has infinite range.
- GeneralClass 12All
What exactly is "force" in physics?
In physics, force is any interaction that changes an object's motion—either starting it, stopping it, speeding it up, slowing it down, or changing its direction. Measured in Newtons (N), force is defined by Newton's Second Law: F = m × a (force euals mass times acceleration). Force is a vector, meaning it has both magnitude and direction. Forces can be contact forces (like pushing) or field forces (like gravity acting at a distance).