TARGET IIT JEE
ONE OR MORE THAN ONE OPTION MAY BE CORRECT Take approx 3 minutes for answering each question.
Q.1 A student calculates the acceleration of m1 in figure shown as a1 = 2 1 2 1 m m g ) m m ( + −
. Which assumption is not required to do this calculation. (A) pulley is frictionless (B) string is massless
(C) pulley is massless (D) string is inextensible
Q.2 Which graph shows best the velocity-time graph for an object launched vertically into the air when air resistance is given by | D | = bv? The dashed line shows the velocity graph if there were no air resistance.
(A) (B) (C) (D)
Q.3 To paint the side of a building, painter normally hoists himself up by pulling on the rope A as in figure. The painter and platform together weigh 200N. The rope B can withstand 300N. Then
(A) The maximum acceleration that painter can have upwards is 5m/s2.
(B) To hoist himself up, rope B must withstand minimum 400N force. (C) Rope A will have a tension of 100 N when the painter is at rest.
(D) The painter must exert a force of 200N on the rope A to go downwards slowly. Q.4 Two men of unequal masses hold on to the two sections of a light rope passing
over a smooth light pulley. Which of the following are possible?
(A) The lighter man is stationary while the heavier man slides with some acceleration (B) The heavier man is stationary while the lighter man climbs with some acceleration (C) The two men slide with the same acceleration in the same direction
(D) The two men move with accelerations of the same magnitude in opposite directions Q.5 Adjoining figure shows a force of 40 N acting at 30° to the horizontal on a body
of mass 5 kg resting on a smooth horizontal surface. Assuming that the acceleration of free–fall is 10 ms–2, which of the following statements A, B, C,
D, E is (are) correct?
[1] The horizontal force acting on the body is 20 N
[2] The weight of the 5 kg mass acts vertically downwards [3] The net vertical force acting on the body is 30 N
(A) 1, 2, 3 (B) 1, 2 (C) 2 only (D) 1 only
Q.6 An iron sphere weighing 10 N rests in a V shaped smooth trough whose sides form an angle of 60° as shown in the figure. Then the reaction forces are
(A) RA = 10 N & RB = 0 in case (i) (B) RA = 10 N & RB = 10 N in case (ii)
(C) RA = 3 20 N & RB = 3 10 N in case (iii) (D) RA = 10 N & RB = 10 N in all the three cases
Quest
Q.7 For ordinary terrestrial experiments, which of the following observers below are inertial. (A) a child revolving in a " giant wheel".
(B) a driver in a sports car moving with a constant high speed of 200 km/h on a straight road. (C) the pilot of an aeroplane which is taking off.
(D) a cyclist negotiating a sharp turn.
Q.8 A long plank P of the mass 5 kg is placed on a smooth floor. On P is placed a block Q of mass 2 kg. The coefficient of friction between P and Q is 0.5. If a horizontal force 15N is applied to Q, as shown, and you may take g as 10N/kg.
(A) The reaction force on Q due to P is 10N (B) The acceleration of Q relative to P is 2.5 m/s2
(C) The acceleration of P relative to the Floor is 2.0 m/s2
(D) The acceleration of centre of mass of P + Q system relative to the floor is (15/7)m/s2
Q.9 The coefficient of friction between 4kg and 5 kg blocks is 0.2 and between 5kg block and ground is 0.1 respectively. Choose the correct statements
(A) Minimum force needed to cause system to move is 17N
(B) When force is 4N static friction at all surfaces is 4N to keep system at rest (C) Maximum acceleration of 4kg block is 2m/s2
(D) Slipping between 4kg and 5 kg blocks start when F is 17N
Q.10 In a tug–of–war contest, two men pull on a horizontal rope from opposite sides. The winner will be the man who
(A) exerts greater force on the rope (B) exerts greater force on the ground
(C) exerts a force on the rope which is greater than the tension in the rope (D) makes a smaller angle with the vertical
Q.11 A man balances himself in a horizontal position by pushing his hands and feet against two parallel walls. His centre of mass lies midway between the walls. The coefficients of friction at the walls are equal. Which of the following is not correct?
(A) He exerts equal forces on walls
(B) He exerts only horizontal forces on the walls (C) The forces of friction at the walls are equal
(D) The forces exerted by the walls on him are not horizontal
Q.12 A man pulls a block heavier than himself with a light horizontal rope. The coefficient of friction is the same between the man and the ground, and between the block and the ground
(A) The block will not move unless the man also moves (B) The man can move even when the block is stationary
(C) If both move, the acceleration of the man is greater than the acceleration of the block (D) None of the above assertions is correct
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Q.13 The two blocks A and B of equal mass are initially in contact when released from rest on the inclined plane. The coefficients of friction between the inclined plane A and B are µ1 and µ2 respectively. (A) If µ1 > µ2, the blocks will always remain in contact.
(B) If µ1 < µ2, the blocks will slide down with different accelerations. (if blocks slide)
(C) If µ1 > µ2, the blocks will have a common acceleration 2 1
(µ1+µ2) g sin θ. (D) If µ1 < µ2, the blocks will have a common acceleration
2 1 2 1 g µ + µ µ µ sin θ. Question No. 14 to 16 (3 questions)
Imagine the situation in which the given arrangement is placed inside a trolley that can move only in the horizontal direction, as shown in figure. If the trolley is accelerated horizontally along the positive x-axis with a0,
then
Q.14 Choose the correct statement(s).
(A) There exists a value of a0 = β at which friction force on block M becomes zero
(B) There exists two values of a0 = (β + α) and (β – α) at which the magnitudes of friction acting on block M are equal
(C) The maximum value of static friction force acts on the block M at two accelerations a1 and a2 such that a1 + a2 = 2β
(D) The maximum value of friction is independent of the acceleration a0.
Q.15 If amin and amax are the minimum and maximum values of a0 for which the blocks remain stationary with respect to the surface, then identify the correct statements
(A) If a0 < amin, the block m accelerates downward (B) If a0 > amax, the block m accelerates upward
(C) The block m does not accelerate up or down when amin ≤ a0 ≤ amax (D) The friction force on the block M becomes zero when a0 =
2 a amin + max Q.16 Identify the correct statement(s) related to the tension T in the string
(A) No value of a0 exists at which T is equal to zero (B) There exists a value of a0 at which T = mg (C) If T < mg, then it must be more than µMg (D) If T > mg, then it must be less than µMg Question No. 17 to 20 (4 questions)
In figure, two blocks M and m are tied together with an inextensible and light string. The mass M is placed on a rough horizontal surface with coefficient of friction µ and the mass m is hanging vertically against a smooth vertical wall.
The pulley is frictionless.
Q.17 Choose the correct statement(s)
(A) The system will accelerate for any value of m (B) The system will accelerate only when m > M (C) The system will accelerate only when m > µM (D) Nothing can be said
Quest
Q.18 Choose the correct statement(s) related to the tension T in the string
(A) When m < µM, T = mg (B) When m < µM, T = Mg
(C) When m > µM, µMg < T < mg (D) When m > µM, mg < T < µMg
Q.19 Imagine a situation in which the given arrangement is placed inside an elevator that can move only in the vertical direction and compare the situation with the case when it is placed on the ground. When the elevator accelerates downward with a0(< g), then
(A) the limiting friction force between the block M and the surface decreases (B) the system can accelerate with respect to the elevator even when m < µM (C) the system does not accelerate with respect to the elevator unless m > µM (D) the tension in the string decreases
Q.20 When the downward acceleration of the elevator becomes equal to g, then (A) both the blocks remain stationary with respect to the elevator
(B) both the blocks accelerate vertically downwards with g with respect to ground (C) the tension in the string becomes equal to zero
(D) the friction force between the block M and the surface is zero Question No. 21 to 27 ( 7 questions)
A block of mass M is placed on a horizontal surface and it is tied with an inextensible string to a block of mass, as shown in figure. A block of mass
m0 is also placed on M
Q.21 If there is no friction between any two surfaces, then (A) the downward acceleration of the block m is
M m m mg 0+ +
(B) the acceleration of m0 is zero
(C) If the tension in the string is T then Mg < T < mg (D) all the above
If a friction force exist between block M and the horizontal surface with the coefficient of friction µ. Q.22 The minimum value of µ for which the block m remains stationary is
(A) M m (B) 0 m M m + (C) M m M+ 0 (D) 0 m M M +
Q.23 If µ < µmin (the minimum friction required to keep the block m stationary), then the downward acceleration of m is (A) g M m M m + µ − (B) m m M g ) M m ( m 0 0 + + + µ − (C) g M m ) M m ( m 0 + + µ − (D) g M m m M m 0 + + µ − Q.24 In previous problem, the tension in the string will be
(A) g M m mM + (B) m m Mg ) M m ( m 0 0 + + + (C) Mg M m ) M m ( m 0 + + µ + (D) g M m ) M m ( m mM 0 + + µ +
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Q.25 If µ0 be the coefficient of friction between the block M and the horizontal surface then the minimum value of m0 required to keep the block m stationary is
(A) m −µ M (B) mµ− M (C) m +µ M (D) mµ+ M
Q.26 If friction force exists between the block M and the block m0 and not between the block M and the horizontal surface, then the minimum value of µ for which the block m remains stationary is
(A) 0 m m (B) m M m 0+ (C) M m m− 0 (D) none of these
Q.27 The minimum value of µ between the block M and m0 (taking horizontal surface frictionless) for which all the three blocks move together, is
(A) m m M m 0+ + (B) m M m + (C) m m M m 0 0 + + (D) none of these
Question No. 28 to 31 (4 questions)
Imagine a situation in which the horizontal surface of block M0 is smooth and its vertical surface is rough with a coefficient of friction µ. Q.28 Identify the correct statement(s)
(A) If F = 0, the blocks cannot remain stationary
(B) For one unique value of F, the blocks M and m remain stationary with respect to M0 (C) The limiting friction between m and M0 is independent of F
(D) There exist a value of F at which friction force is equal to zero
Q.29 In above problem, choose the correct value(s) of F which the blocks M and m remain stationary with respect to M0 (A) (M0 + M + m)µg (B) m M g ) m M M ( m 0 µ − + + (C) (M0 + M + m) M mg (D) none of these
Q.30 Consider a special situation in which both the faces of the block M0 are
smooth, as shown in adjoining figure. Mark out the correct statement(s) (A) If F = 0, the blocks cannot remain stationary
(B) For one unique value of F, the blocks M and m remain stationary with respect to block M0
(C) There exists a range of F for which blocks M and m remain stationary with respect to block M0 (D) Since there is no friction, therefore, blocks M and m cannot be in equilibrium with respect to M0 Q.31 In above problem, the value(s) of F for which M and m are stationary with respect to M0
(A) (M0 + M + m)g (B) (M0 + M + m) M mg (C) (M0 + M + m) m Mg (D) none of these
Q.32 A particle with constant total energy E moves in one dimension in a region where the potential energy is U(x). The speed of the particle is zero where
(A) U(x) = E (B) U(x) = 0 (C)
dx ) x ( dU = 0 (D) 2 2 dx ) x ( U d = 0
Quest
Q.33 A block of mass m slides down a plane inclined at an angle θ. Which of the following will NOT increase the energy lost by the block due to friction?
(A) Increasing the angle of inclination (B) Increasing the distance that the block travels (C) Increasing the accelertion due to gravity (D) Increasing the mass of the block
Q.34 The potential energy in joules of a particle of mass 1 kg moving in a plane is given by U = 3x + 4y, the position coordinates of the point being x and y, measured in metres. If the particle is initially at rest at (6,4), then
(A) its acceleration is of magnitude 5 m/s2
(B) its speed when it crosses the y-axis is 10 m/s (C) it crosses the y-axis (x = 0) at y = -4
(D) it moves in a straight line passing through the origin (0,0)
Q.35 The potential energy of a particle of mass 5kg moving in the XY plane is given by V= −−−−7x+24y joules, x and y being in metres. Initially at t=0 the particle is at the origin (0,0) moving with a velocity of 6[i(2.4)+j(0.7)] m/s. Then
(A) the magnitude of velocity of the particle at t = 4 sec is 25m/s (B) the magnitude of acceleration of the particle is 5m/s2
(C) the direction of motion of the particle initially at t=0 is at right angles to the direction of acceleration (D) the path of the particle is a circle.
Q.36 A box of mass m is released from rest at position 1 on the frictionless curved track shown. It slides a distance d along the track in time t to reach position 2, dropping a vertical distance h. Let v and a be the instantaneous speed and instantaneous acceleration, respectively, of the box at position 2. Which of the
following equations is valid for this situation?
(A) h = vt (B) h = (1/2)gt2 (C) d = (1/2)at2 (D) mgh = (1/2)mv2
Q.37 A ball of mass m is attached to the lower end of light vertical spring of force constant k. The upper end of the spring is fixed. The ball is released from rest with the spring at its normal (unstretched) length, comes to rest again after descending through a distance x.
(A) x = mg/k (B) x = 2 mg/k
(C) The ball will have no acceleration at the position where it has descended through x/2. (D) The ball will have an upward acceleration equal to g at its lowermost position.
Q.38 A ball is projected vertically upwards. Air resistance & variation in g may be neglected. The ball rises to its maximum height H in a time T, the height being h after a time t
[1] The graph of kinetic energy Ek of the ball against height h is shown in figure 1 [2] The graph of height h against time t is shown in figure 2
[3] The graph of gravitational energy Eg of the ball against height h is shown in figure 3
Which of A, B, C, D, E shows the correct answers?
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Q.39 A spring block system is placed on a rough horizontal floor. The block is pulled towards right to give spring some elongation and released.
(A) The block may stop before the spring attains its mean position. (B) The block must stop with spring having some compression. (C) The block may stop with spring having some compression. (D) It is not possible that the block stops at mean position. Q.40 In the above situation the block will have maximum velocity when
(A) the spring force becomes zero (B) the frictional force becomes zero (C) the net force becomes zero (D) the acceleration of block becomes zero
Q.41 A particle of mass m is at rest in a train moving with constant velocity with respect to ground. Now the particle is accelerated by a constant force F0 acting along the direction of motion of train for time t0. A girl in the train and a boy on the ground measure the work done by this force. Which of the following are
INCORRECT?
(A) Both will measure the same work
(B) Boy will measure higher value than the girl (C) Girl will measure higher value than the boy
(D) Data are insufficient for the measurement of work done by the force F0
Q.42 Two particles move on a circular path (one just inside and the other just outside) with angular velocities ω and 5ω starting from the same point. Then
(A) they cross each other at regular intervals of time ω π 4 2
when their angular velocities are oppositely directed. (B) they cross each other at points on the path subtending an angle of 60oat the centre if their angular
velocities are oppositely directed. (C) they cross at intervals of time π
ω
3 if their angular velocities are oppositely directed.
(D) they cross each other at points on the path subtending 90o at the centre if their angular velocities are
in the same sense.
Q.43 A cart moves with a constant speed along a horizontal circular path. From the cart, a particle is thrown up vertically with respect to the cart
(A) The particle will land somewhere on the circular path (B) The particle will land outside the circular path
(C) The particle will follow an elliptical path (D) The particle will follow a parabolic path Question No. 44 to 46 (3 questions)
A particle of mass m is released from a height H on a smooth curved surface which ends into a vertical loop of radius R, as shown
Q.44 Choose the correct alternative(s) if H = 2R
(A) The particles reaches the top of the loop with zero velocity (B) The particle cannot reach the top of the loop
(C) The particle breaks off at a height H = R from the base of the loop (D) The particle break off at a height R < H < 2R
Quest
Q.45 If θ is instantaneous angle which the line joining the particle and the centre of the loop makes with the vertical, then identify the correct statement(s) related to the normal reaction N between the block and the surface
(A) The maximum value N occurs at θ = 0
(B) The minimum value of N occurs at N = π for H > 5R/2 (C) The value of N becomes negative forπ/2 < θ < 3π/2 (D) The value of N becomes zero only when θ ≥ π/2
Q.46 The minimum value of H required so that the particle makes a complete vertical circle is given by
(A) 5 R (B) 4 R (C) 2.5 R (D) 2 R
Q.47 A small particle of mass m is given an initial high velocity in the horizontal plane and winds its cord around the fixed vertical shaft of radius a. All motion occurs essentially in horizontal plane. If the angular velocity of the cord is ω0 when the distance from the particle to the tangency point is r0, then the angular velocity of the cord ω after it has turned through an angle θ is
(A) ω = ω0 (B) ω = 0 0 r aω (C) ω = 0 0 r a 1− θ ω (D) ω = ω0θ
Q.48 A particle moving with kinetic energy = 3 joule makes an elastic head on collision with a stationary particle which has twice its mass during the impact.
(A) The minimum kinetic energy of the system is 1 joule.
(B) The maximum elastic potential energy of the system is 2 joule.
(C) Momentum and total kinetic energy of the system are conserved at every instant.
(D) The ratio of kinetic energy to potential energy of the system first decreases and then increases. Q.49 A ball of mass m collides elastically with an identical ball at rest with some impact parameter.
(A) 100 % energy transfer can never take place (B) 100 % energy transfer may take place
(C) angle of divergence between the two balls must be 90°
(D) angle of divergence between the two balls depend on impact parameter
Q.50 Two balls A and B having masses 1 kg and 2 kg, moving with speeds 21 m/s and 4 m/s respectively in opposite direction, collide head on. After collision A moves with a speed of 1 m/s in the same direction, then correct statements is :
(A) The velocity of B after collision is 6 m/s opposite to its direction of motion before collision. (B) The coefficient of restitution is 0.2.
(C) The loss of kinetic energy due to collision is 200 J. (D) The impulse of the force between the two balls is 40 Ns.
Q.51 An object comprises of a uniform ring of radius R and its uniform chord AB (not necessarily made of the same material) as shown. Which of the following can not be the centre of mass of the object
(A) (R/3, R/3) (B) (R/3, R/2)
(C) (R/4, R/4) (D) (R 2, R 2)
Q.52 A ball A collides elastically with another identical ball B initially at rest A is moving with velocity of 10m/ s at an angle of 60° from the line joining their centres. Select correct alternative :
(A) velocity of ball A after collision is 5 m/s (B) velocity of ball B after collision is 5 3 m/s (C) velocity of ball A after collision is 7.5 m/s (D) velocity of ball B after collision is 5 m/s.
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Q.53 Consider following statements
[1] CM of a uniform semicircular disc of radius R = 2R/π from the centre [2] CM of a uniform semicircular ring of radius R = 4R/3π from the centre [3] CM of a solid hemisphere of radius R = 4R/3π from the centre
[4] CM of a hemisphere shell of radius R = R/2 from the centre Which statements are correct?
(A) 1, 2, 4 (B) 1, 3, 4 (C) 4 only (D) 1, 2 only
Q.54 The diagram to the right shows the velocity-time graph for two masses R and S that collided elastically. Which of the following statements is true?
(I) R and S moved in the same direction after the collision. (II) Kinetic energy of the system (R & S) is minimum at t = 2 milli sec. (III) The mass of R was greater than mass of S.
(A) I only (B) II only (C) I and II only (D) I, II and III
Q.55 In an inelastic collision,
(A) the velocity of both the particles may be same after the collision (B) kinetic energy is not conserved
(C) linear momentum of the system is conserved.
(D) velocity of separation will be less than velocity of approach.
Q.56 A man of mass 40 kg is standing on a trolley A of mass 140 kg . He pushes another trolley B of same material of mass 60 kg, so that they are set in motion . Then :
(A) speed of trolley A is 3 times that of trolley B immediately after the interaction. (B) speed of trolley B is 3 times that of trolley A immediately after the interaction. (C) distance travelled by trolley B is 3 times that of trolley A before they stop. (D) distance travelled by trolley B is 9 times that of trolley A before they stop.
Q.57 Two identical balls are interconnected with a massless and inextensible thread. The system is in gravity