PG Brainstormer - 3C
PG B r a i n s t o r m e r - 3 C KINEMATICS, NEWTON’S LAWS OF MOTION & FRICTION
An Ultimate Tool to understand advanced High School Physics
Ti m e A ll o w e d
by ASHI ASHISH SH ARORA Sir
6 0 M in
M a x im u m M a rk s
60
Instruction : Each Each question question from 1 to 10 is of 3 Marks and there there is a negative negative marking of -1 Mark. From questions 11 to 16 each question is of 5 Marks with no negative marking. From questions 17 to 28 each question is of 3 Marks and there is a negative marking of -1 Mark.
Section - A Single Choice Correct (Q. No. 1 to 10)
Y X A L A G S C I S Y H P
The Questions given in this section are MCQs with four answer options (A), (B), (C) and (D) out of which ONLY ONE is correct. Choose the correct answer and fill the answer answer in the OMR sheet provided at the end. 1.
The force acting on th thee block is given by F = 5 – 2t. Block is at rest at t = 0. The frictional frictiona l force acting on the block after time t = 2 second s econd will be : ( = 0.2) (A) 2 N (C) 1 N
(B) 3 N
(D) Zero
2.
Shorts are fired at the same instant from the top and bottom bottom of a vertical cliff at angle ang le and and they strike an object simultan eously at the th e same point. If the hor izontal distan ce of the object object from the cliff is l and h be the height of the cliff then : (A) h = l (cot – cot ) (B) h = l (cot – cot ) (C) h = l (tan – tan ) (D) h = l (sin – sin )
3.
A given object takes n times more time to slide down 45° rough in clined plane a s it takes to slide down a perfectly smooth 45° incline. Th e coefficient coefficient of kinetic friction between between the object and the incline is : 1
(A)
1n
2
(B)
1
1
n
2
(C) 1
1
n
1
(D)
2
4.
Pulleys and springs are massless. All blocks are moving with constant acceleration. The reading of spring balance S 1 and S2 will respectively respecti vely be : (A) 2.4 kg, 3.2 kg (B) 2kg, 2k g, 4kg (C) 3.2 kg, 2.4 kg (D) 4kg, 4kg 4kg
5.
A block of mass 2kg has acceleration a
2n
2
4ˆi 3ˆj(m/s2). A frame S 1 is accelerating along positive x-axis with an
acceleration of 4 m/s 2. The magnitude mag nitude of pseudo force that will act on block, when it is observed from the frame S 1 will be : (A) 4N
(B) 8N
(C) 2 1 3 N
(D) 6N
6.
A ball of mass 1 kg is moving with speed 3 m/s. 4 N-S im pulse is given to the ball perpendicular to velocity of ball. Speed of ball just after impulse will be : (A) 1 m/s (B) 5 m/s (C) 7 m/s (D) None of these
7.
A particle is projected projected at an an gle 60º with horizontal with a speed of 10
3 m/s from point A as shown. At the same
time the sufficient su fficient long wedge is made to move with constan t velocity of 10 3 towards right as sh own own in figure. The 2 time in second after which whi ch particle will h it the wedge will be. (g = 10 m/s ). (A) 1 sec (B) 2 sec (C) 3 sec (D) it will never collide on the wedge PHYS ICS
1
8.
9.
PG Brainstormer - 3C Two astronauts, each of mass 75 kg are floating next to each other in space, outside the space shuttle one of them pushes the other through a distance of 1 m (an arms length) with a force of 300 N. What is the final relative velocity of the two ? (A) 2.0 m/s (B) 2.83 m/s (C) 5.66 m/s (D) 4 m/s Three identical cylinders of radius R are in contact. Ea ch cylinder is rotating with angular velocity . A thin belt is moving without sliding on the cylinders. Calculate the magnitude of velocity of point P with respect to Q. P and Q are two points of belt which are in contact with the cylinder. (A) 2R
10.
(B) R
(C) R /2
(D) R 3
An airplane flies northward from town A to town B and then back again . There is a steady wind blowing towards the north so that for the first stage of the trip, th e airplane is flying in th e same direction as the wind and for the return trip of the journey, the airplane is flying directly into the wind. The total trip time T w, as compared to the total trip time in the absence of any wind T 0. (A) Tw = T0 (B) Tw > T0 (C) Tw < T0 (D) Tw = 2T0
Y X A L A G S C I S Y H P Section - B More than one Choice Correct (Q. No. 11 to 16)
The Questions given in this section are MCQs with four answer options (A), (B), ( C) and (D) out of which ONE or MORE than ONE answers may be correct. Choose all the correct answer options and fill the answer in the OMR sheet provided at the end. You will get marks in a question only if all the answer options of that question are chosen by you. 11.
Man A sitting in a car moving with 54 km/hr observes man B in front of car crossing perpend icularly the road of width 15 m in 3 s. (A) Speed of man B is 5 10 m/s (B) Speed of man B is 5 ms –1
1 with direction of motion of car 3
(C) Actual direction of motion of B is at an angle of tan –1
(D) Actual direction of motion of B is at an an gle of tan –1(3) with direction opposite to the direction of motion of car 12.
Two small balls A and B are laun ched in the same vertical plan e simultaneously, with same speed of 20 m/s at t = 0. Ball A has an initial horizontal velocity and ball B has initial velocity at an angle above the line joining A and B as shown. If th e projectiles collide in mid-air at time t, then : (A) = 30° (B) = 60° 20
(C) t =
13.
3
10
s
(D) t =
3
s
ABCD is a wire frame of identical wires in which poin t D is given velocity v as shown in figure. Choose the correct statement (s) : (A) Velocity of point A along x-axis will be v/2. (B) Speed of point A will be v
(C) Speed of point A along y-axis will be v/2
(D) Velocity of point A will be equa l to velocity of point C 14.
A 10 kg block is resting on a rough horizontal surface. The Force F is a pplied on it for 4s. The var iation of force with time is shown in the figure. (µs = µk = 0.5, g = 10 m/s2). Then
F (N)
10 kg
F 100 N
4s (A) At t = 1 sec, velocity of block is 5 m/s (C) At t = 4 sec, velocity of block is 20 m/s PHYSICS
t (sec)
(B) At t = 1 sec, velocity of block is zero (D) At t = 4 sec, velocity of block is 5 m/s 2
15.
PG Brainstormer - 3C In the situation shown pulley and string ar e ideal. Mass of man is 2m an d mass of the block is m. If a 1 is the relative acceleration of man w.r.t rope in upward direction then : (A) Acceleration of man w.r.t. ground is
a1 g 3
(B) Acceleration of block w.r.t groun d is
g 2a 1 3
(C) Acceleration of man w.r.t ground is
T
a1 g 3
(D) Acceleration of block w.r.t ground is
16.
T
2a 1 g 3
Y X A L A G S C I S Y H P
A person applies a constant force F on a particle of mass m and finds that the particle moves in a circle of radius r with a uniform speed v as seen (in the plane of motion) from an inertial frame of reference. Select the correct statement. (A) This is not possible (B) There are other forces on the particle (C) The resultant of the other forces is mv 2/r towards the centre (D) The resultant of the other forces varies in magnitude as well as in direction
*****
PHYSICS
3
PG Brainstormer - 3C
PG B r a i n s t o r m e r - 3 C KINEMATICS, NEWTON’S LAWS OF MOTION & FRICTION
An Ultimate Tool to understand advanced High School Physics
Time Allow ed
by ASHISH ARORA Sir
60 M in
M a ximum M a rks
60
Y X A L A G S C I S Y H P
OMR Sheet for the PG Brainstormer - 3C (MECHANICS) A
PHYSICS
B
C
D
A
1
9
2
10
3
11
4
12
5
13
6
14
7
15
8
16
B
C
D
4
PG B r a i n s t o r m e r - 3 C KINEMATICS, NEWTON’S LAWS OF MOTION & FRICTION
An Ultimate Tool to understand advanced High School Physics
Time Allow ed
by ASHISH ARORA Sir
60 M in
M a ximum M a rks
60
A N S W ER K E Y 1. (A) 10. (B)
2. (C) 11. (A,C)
3. (C) 12. (A,D)
4. (A) 13. (A,B)
5. (B) 14. (B,D)
6. (B) 15. (A,B)
7. (B) 16. (B,D)
8.
(D)
9.
(D)
