101) Electron microscope is designed by “knoll” and “Ruska”.
102) The Refractive index of Diamond is 2.41
103) Density of diamond is 3.51gm/cm3
104) Density of graphite is 2.25gm/cm3
105) Third form of carbon C-60 is discovered in 1996 by
“HW.KROTO”; “Resmasy”.
106) Distance between two layers in graphite is ----3.35Ao
107) C-C bond length ------1.42A in graphite.
108) C-C bond length -------1.52Ao in diamond.
109) Radioactivity was discovered by Henry
Becquerel in 1896.
110) To avoid overturning of a vehicle moving on a curved
road, the height of center of gravity of vehicle must be nearer to the ground.
111)When a spin bowler throws a cricket ball towards the
batsman , the center of mass of ball follows a parabolic path.
112) Newton’s laws of motion apply only to centre of mass.
113) A body is heated uniformly keeping it on a smooth
surface . the position of centre of mass wrt that body doesn't change in
position.
114)Two balls are thrown simultaneously in air the
acceleration of centre of mass of those two balls in air is equal to ‘g’.
115)If two particles initially at rest approach each other
due to mutual force, they two meet at centre of mass of system.
116) The center of mass of Earth and moon describes elliptical path.
117)When a person walks on a rough road , the frictional force exerted by the road on him is along his direction of motion.
118)Less mileage is obtained per liter of fuel by a car making
frequent stops because each time of starting it has to overcome static
friction.
119)Small brake and large brake both are equally effective in
stopping a cycle as friction doesn’t depend on area of contact.
120)Coefficient of friction can be greater than 1.
121)When a person walks on a rough surface reaction of force
applied by a man on surface keeps him
moving.
122) Helium has the lowest critical temp -268 oC of all
known gases.
123) Helium has no triple point.
124) Boiling point of Helium is 4.2 Kelvin.
125) No white Dwarf star can have mass larger than 1.4 times mass of
sun.
126) Work done by Contripetal force is zero.
127) Centripetal force and centrifugal reaction from action –
reaction pair. But centripetal force and centrifugal force doesn’t form action –reaction pair.
128) Centrifugal force is a pseudo force.
129) Centripetal force & Centrifugal reaction are Real forces.
130) Mass of earth is 6x1024 kg
131) Mean density of earth is about 5500kg/m3
132) Mean radius of earth is about 6400km.
133) Acceleration due to gravity depends on density of planet.
134) ’g ‘ is maximum on Jupiter.
135) ‘g’ is minimum on mercury.
136) Orbital velocity for a surface satellite is about 8 km/sec.
137) The orbit in which a geostationary satellite moves is
called Parking orbit.
138) Relative velocity of parking
satellite wrt earth is zero.
139) Time period of revolution of parking satellite 24hrs.
140) Orbital linear velocity is about 3kms-1.
141) A satellite cannot be coast in a stable orbit in a plane not
passing through the earth’s centre.
142) Communication satellites are placed in Parking orbits.
143) Time period of revolution of a satellite around planet is
independent of mass of satellite.
144) Time period of a surface satellite of earth is 84.6 min or
1.4 hrs
145) If a rocket is launched in the equatorial plane from west to
east , advantage is upto 0.47 kms-1 in launching speed.
146) Negative total energy of satellite indicates that energy
must be supplied to remove the satellite from the orbit against gravitational
attraction.
147) Apparent weight of a body in satellite is zero.
148) If 1 kg of sugar is weighed using a spring balance at
poles and the equator more quantity is
obtained at equator.
149) For geostationary satellite the time period is equal to
rotation of earth about its axis.
150)The first artifiacial satellite launched by India is
Aryabhatta in 1975, April 19.
