##### Physics Page-9

81) A car and a loaded truck are moving with the same speed along a road. As compared to the truck, the car shall possess
(A) More kinetic energy
(B) More potential energy
(C) Less kinetic energy
(D) More mechanical energy

82) When a moving bus stops suddenly, the passengers are pushed forward because of the
(A) Friction between the earth and the bus
(B) Friction between the passengers and the earth
(C) Inertia of the passengers
(D) Inertia of the bus

83) Erect and virtual images are always produced by
(A) Plane and convex mirrors
(B) Plane mirrors alone
(C) Concave and convex mirrors
(D) Concave mirrors alone

84) The working of the receiver of a telephone depends upon the
(A) Change in magnetization of an electromagnet, which causes a diaphragm to vibrate.
(B) Efficiency of the loudspeaker which enhances the loudness of sound.
(C) Conversion of the electric signal, after its amplification into sound wave.
(D) Diaphragm which is made to vibrate by the incoming sound wave.

85) An old man, unable to apply a large force, wishes to use a screw jack for lifting his car wheels. If L is the length of the rod used to turn the jack and p is the pitch of jack screw, then he should use a jack in which
(A) L is large and p is also large
(B) L is small and p is large
(C) L is large and p is small
(D) L is small and p is small

86) The hydraulic brakes used in automobiles is a direct application of:
(A) Archimedes' principle
(B) Toricellian law
(C) Bernoulli's theorem
(D) Pascal's law

87) In T.V transmission:
(A) Sound and video signals are transmitted simultaneously
(B) Sound is transmitted first and then the video signal follows
(C) Video signal is transmitted first, followed by sound signal
(D) Sound and video signals are transmitted from different places at the same time

88) Surface tension in a liquid is due to
(A) Adhesive force between the molecules
(B) Cohesive force between the molecules
(C) Gravitational force between the molecules
(D) Electrical force between the molecules

89) Springs of shock absorbers of automobiles and railway coaches are made of steel and not of rubber because steel is
(A) More durable than rubber
(B) Less expensive than rubber in the long run
(C) Less elastic than rubber
(D) More elastic than rubber

90) Why does the mercury column in the barometer fall rapidly before a severe storm?
(A) It is due to decrease in humidity in air
(B) It is due to the rise in atmospheric pressure
(C) It is due to the fall in atmospheric pressure
(D) It is due to the severe heat energy from the sun