2018-10-01_Physics_For_You

1. In two systems of relations among velocity,

acceleration, and force are, respectively, vv 2

2

= 1

α

β

,

a 2 = DEa 1 , and F

F

2

=^1

αβ

. If D and E are constants,
then correct relation among mass, length, and time
in two systems is

(a) TT 21 = α 2

β

(b) M

M

2

1

=αβ 22

(c) LL 21 = α 2

β

(d) Both (a) and (b)

2. Shots are red simultaneously
   from the top and bottom of a
   vertical cli with the elevation
   D = 30°, E = 60°, respectively
   gure. e shots strike an
   object simultaneously at the
   same point. If a= 30 3m is
   the horizontal distance of the object form the cli,
   then the height h of the cli is
   (a) 30 m (b) 45 m (c) 60 m (d) 90 m


3. In the gure shown a plank of length l = 64 m, mass
   m 2 = 5 kg rests on a smooth surface. Upper surface
   of block is rough with coecient of kinetic friction
   Pk = 0.5 and Ps = 0.6. A force F of magnitude 30 N is
   applied on block m 1. What is displacement of plank
   till the small block falls over from plank?

m 2

F m 1 Rough

Smooth

L

(a) 0.6 m (b) 10 m (c) 16 m (d) 2.5 m

4. A lead bullet just melts when stopped by an obstacle.
   Assuming that 25 percent of the heat is absorbed by
   the obstacle, nd the velocity of the bullet. Its initial
   temperature is 27°C.
   (Melting point of lead = 327°C, specic heat of
   lead = 0.03 cal g–1 °C–1, latent heat of fusion of lead
   = 6 cal g–1 °C–1, J = 4.2 joule calorie–1).

h

E

D

a= 30 3m

(a) 300 m s–1 (b) 409.8 m s–1

(c) 1100 m s–1 (d) 25 m s–1

5. A carpet of mass M, made of inextensible, material
   is rolled along its length in the form of a cylinder
   of radius R and is kept on a rough oor. e carpet
   starts unrolling without sliding on the oor when
   a negligibly small push is given to it. Calculate the
   horizontal velocity of the axis of the cylindrical part
   of the carpet when its radius reduces to R/2.

(a)

14

3

Rg

(b) gR

(c) 3 gR (d) 5 gR

6. A body is projected vertically upwards from the
   bottom of a crater of moon of depth R/100 where
   R is the radius of moon with a velocity equal to the
   escape velocity on the surface of moon. Calculate
   maximum height attained by the body from the
   surface of the moon.
   (a) 150 R (b) 99 R (c) 50 R (d) 199 R


7. A drop of water of mass 0.2 g is placed between two
   glass plates. e distance between them is 0.01 cm.
   Find the force of attraction between the plates if
   surface tension of water = 0.07 N m–1.
   (a) 2.8 N (b) 3.5 N (c) 0.7 N (d) 1.25 N


8. A column of mercury of length 10 cm is contained
   in the middle of a horizontal tube of length 1 m
   which is closed at both the ends. e two equal
   lengths contain air at standard atmospheric pressure
   of 0.76 m of mercury. e tube is now turned to
   vertical position. By what distance will the column
   of mercury be displaced?
   (a) 3.14 cm (b) 1.28 cm
   (c) 2.95 cm (d) 4.83 cm


9. A thermostated chamber at a height h above earth's
   surface maintained at 30°C has a clock tted with
   uncompensated pendulum. e maker of the clock
   for chamber mistakenly designed it to maintain
   correct time at 20°C. It is found that when the
   chamber is brought to earth's surface the clock in it

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