Tag: science & technology

At Earth's exact center, gravity becomes zero because you're equally surrounded by mass in all directions. The gravitational pull from all sides cancels out completely. Gravity increases slightly as you go down from surface to the mantle, then decreases toward zero at the center.

Stars appear to twinkle (scintillation) because Earth's atmosphere has varying temperature and density layers that refract starlight differently as it passes through. This causes the light to bend and flicker. The option calls this 'pollution' but means atmospheric disturbance - the explanation is correct even if the wording is imprecise.

In a perfectly insulated closed room, a fan increases temperature. The fan's motor converts electrical energy to heat, and the air friction from the fan blades also generates thermal energy. While fans cool people by evaporation, they add net heat to a closed system.

The Sun produces energy through nuclear fusion, where hydrogen nuclei combine to form helium. This process converts mass to energy according to E=mc², releasing enormous heat and light. Fission is incorrect (that's splitting atoms), and the helium-to-hydrogen direction is backwards.

Negative acceleration means the acceleration vector points in the negative direction. Whether the object slows down or speeds up depends on the direction of its velocity - if velocity and acceleration have opposite signs, it slows down; if they have the same sign, it speeds up.

The total normal force you exert on the floor equals your weight (mg) in both cases, whether you're standing or lying down. This is a consequence of Newton's laws - the floor must push up with a force equal to your weight to support you. The difference is in pressure, not total force.

ISRO (Indian Space Research Organisation) has its headquarters in Bangalore (now Bengaluru). Delhi is the capital but not ISRO HQ, Thiruvananthapuram has Vikram Sarabhai Space Centre, and Sriharikotta is the launch pad.

Chandrayaan-1 was launched on October 22, 2008 using PSLV C11 rocket. PSLV C7 and C13 launched other satellites, and GSLV Mk II (not GSLV 11) is a different rocket class.

Rakesh Sharma became the first Indian to travel to space on April 2, 1984, as part of the Soviet Intercosmos program. He flew aboard Soyuz T-11 to the Salyut 7 space station.

Kalpana-1 was India's first dedicated meteorological satellite, launched in 2002. It provided weather monitoring and cyclone warning services. Options A and D are incorrect - Kalpana-1 was neither a spaceship nor a lunar mission. Option B (geosynchronous) is also incorrect; while it was in geostationary orbit, its primary classification was meteorological, not just a communication satellite.