Tiêu đề LAWS OF MOTION.pdf ✅

P a g e | 1 5.LAWS OF MOTION Single Correct Answer Type 1. An ice cart of mass 60 kg rests on a horizontal snow patch with coefficient of static friction1 3 . Assuming that there is no vertical acceleration, find the magnitude of the maximum horizontal force required to move the ice cart (g = 9.8 ms−2 ) a) 100 N b) 110 N c) 209 N d) 196 N 2. A monkey of mass 20 kg is holding a vertical rope.The rope will not break when a mass of 25 kg is suspended from it but will break if the mass exceeds 25 kg. What is the maximum acceleration with which the monkey can climb up along the rope (g = 10 m/s 2 ) a) 10 m/s 2 b) 25 m/s 2 c) 2.5 m/s 2 d) 5 m/s 2 3. A player kicks a football of mass 0.5 kg and the football begins to move with a velocity of 10 m/s. If the contact between the leg and the football lasts for 1 50 s, then the force on the ball should be a) 2500 N b) 1250 N c) 250 N d) 625 N 4. An 80 kg person is parachuting and is experiencing a downward acceleration of 2.8ms−2 . The mass of the parachute is 5 kg. The upward force on the open parachute is (Take g = 9.8ms−2 ) a) 595 N b) 675 N c) 456 N d) 925 N 5. A block of mass 15 kg is resting on a rough inclined plane as shown in figure. The block is tied by a horizontal string which has a tension of 50 N. The coefficient of friction between the surfaces of contact is (g = 10 ms −2 ) a) 1/2 b) 3/4 c) 2/3 d) 1/4 6. The rate of the mass of the gas emitted from rear of a rocket is initially 0.1kgs−1 . If the speed of the gas relative to the rocket is 50 ms−1 and mass of the rocket is 2 kg, then the acceleration of the rocket (in ms−2 ) is a) 5 b) 5.2 c) 2.5 d) 25 7. A 100 kg block is suspended with the help of three string A, B and C. The tension in the string C is a) 50 gN b) 100 gN c) 20 gN d) 20 gN 8. If the resultant of all the external forces acting on a system of particles is zero, then form an inertial frame, one can surely say that a) Linear momentum of the system does not change in time b) Kinetic energy of the system does not change in time c) Angular momentum of the system does not change in time d) Potential energy of the system does not change in time 9. Which of the following quantities measured from different inertial reference frames are same
P a g e | 2 a) Force b) Velocity c) Displacement d) Kinetic energy 10. Maximum value of static friction is called a) Limiting friction b) Rolling friction c) Normal reaction d) Coefficient of friction 11. Two bodies of mass 4 kg and 6 kg are attached to the ends of a string passing over a pulley. The 4 kg mass is attached to the table by another string. The tension in this string T1 is a) 19.6 N b) 25 N c) 10.6 N d) 10 N 12. A vessel containing water is given a constant acceleration a towards the right, along a straight horizontal path. Which of the following diagram represents the surface of the liquid a) A b) B c) C d) D 13. A marble block of mass 2 kglying on ice when given a velocity of 6 m/s is stopped by friction in 10s. Then the coefficient of friction is a) 0.01 b) 0.02 c) 0.03 d) 0.06 14. Which of the following is the correct order of forces a) Weak mg μ c) α > g μm d) α ≥ g μ 16. A block of mass m1 reacts on a horizontal table. A string tied to the block is passed on a frictionless pulley fixed at the end of the table and to the other end of string is hung another block of mass m2. The acceleration of the system is a) m2g (m1 + m2) b) m1g (m1 + m2) c) g d) m2g m1 17. If a street light of mass M is suspended from the end of a uniform rod of length L in different possible patterns as shown in figure, then a a a a (A) (B) (C) (D)
P a g e | 3 a) Pattern A is more sturdy b) Pattern B is more sturdy c) Pattern C is more sturdy d) All will have same sturdiness 18. If a ladder weighing 250 N is placed against a smooth vertical wall having coefficient of friction between it and floor is 0.3, then what is the maximum force of friction available at the point of contact between the ladder and the floor a) 75 N b) 50 N c) 35 N d) 25 N 19. A particle of mass m moving with velocity u makes an elastic one dimensional collision with a stationary particle of mass m. They are in contact for a very short time T. Their force of interaction increases from zero to F0 linearly in time T/2, and decreases linearly to zero in further time T/2. The magnitude of F0 is a) mu/T b) 2mu/T c) mu/2T d) None of these 20. Pulling force making an angle θ to the horizontal is applied on a block of weight W placed on a horizontal table. If the angle of friction is α, then the magnitude of force required to move the body is equal to a) W sinα g tan(θ − α) b) W cos α cos(θ − α) c) W sin α cos(θ − α) d) W tan α sin(θ − α) 21. Two blocks of masses m1 = 4 kg and m2 = 2 kg are connected to the ends of a string which passes over a massless, frictionless pulley. The total downwards thrust on the pulley is nearly a) 27 N b) 54 N c) 0.8 N d) Zero 22. Consider the following statement. When jumping from some height, you should bend your knees as you come to rest instead of keeping your legs stiff. Which of the following relations can be useful in explaining the statement? a) ∆p1 = −∆p2 b) ∆E = −∆(PE + KE) = 0 c) F ∆t = m∆v d) ∆x ∝ ∆F Where symbols have their usual meaning 23. At a certain instant of time the mass of rocket going up vertically is 100 kg. If it is ejecting 5 kg of gas per second at a speed of 400 m/s, the acceleration of the rocket would be (Taking g = 10 m/s 2 ) a) 20 m/s 2 b) 10 m/s 2 c) 2 m/s 2 d) 1 m/s 2 24. Two masses A and B of 10 kg and 5 kg respectively are connected with a string passing over a frictionless T/2 F t F0 T
P a g e | 4 pulley fixed at the corner of a table as shown. The coefficient of static friction of A with table is 0.2. The minimum mass of C that may be placed on A to prevent it from moving is a) 15 kg b) 10 kg c) 5 kg d) 12 kg 25. A bullet of mass 5 g is shot from a gun of mass 5 kg. The muzzle velocity of the bullet is 5000 ms−1 . The recoil velocity of the gun is a) 0.5 ms−1 b) 0.25 ms−1 c) 1 ms−1 d) Data is insufficient 26. The masses of 10 kg and 20 kg respectively are connected by a massless spring as shown in figure. A force of 200 N acts on the 20 kg mass. At the instant shown, the 10 kg mass has acceleration 12 m/sec2 . What is the acceleration of 20 kg mass a) 12 m/sec2 b) 4 m/sec2 c) 10 m/sec2 d) Zero 27. A steel wire can withstand a load up to 2940 N. A load of 150 kg is suspended from a rigid support. The maximum angle through which the wire can be displaced from the mean position, so that the wire does not break when the load passes through the position of equilibrium, is a) 30° b) 60° c) 80° d) 85° 28. The upper half of an inclined plane of inclination θ is perfectly smooth while the lower half is rough. A body starting from the rest at top comes back to rest at the bottom if the coefficient of friction for the lower half is given by a) μ = sin θ b) μ = cot θ c) μ = 2 cos θ d) μ = 2 tan θ 29. Which of the four arrangements in the figure correctly shows the vector addition of two forces F1 ⃗⃗⃗ and F2 ⃗ to yield the third force F3 ⃗ a) b) c) d) 30. A particle moves in the x − y plane under the influence of a force such that its linear momentum is p (t) = A[îcos(kt) − ĵsin(kt)] Where A and k are constants. The angle between the force and momentum is a) 0° b) 30° c) 45° d) 90° 31. The spring balance inside a lift suspends an object. As the lift begins to ascent, the reading indicated by the spring balance will a) Increase b) Decrease c) Remain unchanged d) Depend on the speed of ascend 32. Two blocks of equal masses m are released from the top of a smooth fixed wedge as shown in the figure. The acceleration of the centre of mass of the two blocks is a) g b) g 2 c) 3g 4 d) g √2 F3  F1  F1  F1  F3  F1  F3  F1  F2  F3  F1  F2  10 kg 20 kg 200N