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question_answer1) Which one has greater inertia - an ant or an elephant?
question_answer2) Two cars 'A' and 'B' of same masses are moving with velocities V and 2 V respectively. What is the ratio of their inertia?
question_answer3) Match the following: Column I Column II (i) A gril jumping out of a speeding van may (p) Inertia of rest fall forward (ii) Apples fall on shaking a tree (q) Inertia of motion (iii) While sharpening a knife, sparks fly off tangentially from the grinding stone. (r) Inertia of direction (iv) When a rotating fan is switched off it continues to rotate (v) A passenger sitting in a bus gets a backward jerk when the bus starts suddenly.
question_answer4) Explain the following: (A) When a carpet is beaten with a stick, dust comes out. (D) Athletes often fail to stop themselves before the line. (C) Some leaves may get detached from a tree if we vigorously shake its branch. (L) In oil tankers some space is left at the top while filling them.
question_answer5) What is the momentum of man of mass 75 kg when he walks with a uniform velocity of 2 m/s?
question_answer6) What will be the momentum of a toy car of mass 200 g moving with a speed of 5 m/s?
question_answer7) If two bodies A and B of same mass are moving with velocities V and 3 V respectively, then find the ratio of their momentum.
question_answer8) A body of mass 20 kg moving with a velocity of 10 m/s is brought to rest after some time. Find the change in momentum of the body.
question_answer9) When a sphere of mass 5 kg strikes a wall with a velocity of 5 m/s, it rebounds with the same velocity: (a) What is the momentum of the sphere before striking and after rebounding? (b) Also find the change in momentum of the sphere?
question_answer10) If two balls of equal mass are moving towards each other with the same velocity, what is the total momentum of the system?
question_answer11) Momentum of a copper sphere of radius r units is \[x\] units, then momentum of another copper sphere of radius 2r units moving with the same velocity is \[2x\] units. (T/F).
question_answer12) A body starting from rest is moving at constant acceleration. After travelling a certain distance 10 m, its momentum is 50 N-s. What would be the momentum of the body after travelling 20 meters?
question_answer13) There are two bodies of masses 10 kg and 5 kg respectively. Find the ratio of the force acting on them if their velocity-time graphs are as shown below: [Hint: \[slope=\tan \theta \] ]
question_answer14) The masses of two spheres is 3 kg and 4 kg respectively. When a force is applied on the first body, it moves with an acceleration of\[\text{6m}/{{\text{s}}^{\text{2}}}\]. How much acceleration will the same force produce in the other body?
question_answer15) It is required to increase the speed of a scooter of 80 kg from 5 m/s to 25 m/s in 2 seconds. How much force is required?
question_answer16) Which would require a greater force accelerating a body of 10 g mass at \[\text{5 m}/{{\text{s}}^{\text{2}}}\]or a body of 20 g mass at\[\text{2 m}/{{\text{s}}^{\text{2}}}\]?
question_answer17) A car of mass 'm' kg and a truck of mass ?10 m? kg are moving with the same velocity. The force required to stop the car in a certain distance is 'F' N. Then the force required to stop the truck through the same distance is ______.
question_answer18) The velocity-time graph of a moving particle is shown in the figure. How much force acts on the body?
question_answer19) A force 20 N acts on a cube producing an acceleration of \[5\,m/{{s}^{2}}\]. Find the density of the material of the cube, if its volume is \[\text{1 }{{\text{m}}^{\text{3}}}\]?
question_answer20) A gun fires 216 bullets per minute. The mass of each bullet is 50 g and velocity of each bullet is 1000 m/ s. Find the force required to hold the gun.
question_answer21) A force of 10 N is needed to produce certain acceleration in a gold sphere of radius 10 cm. find the force required to produce same acceleration in sphere made of same material of radius 20 cm.
question_answer22) In a cricket match between India and South Africa, the Indian player defends a ball from South African player which is thrown with a speed of 20m/s. After striking the Indian player's bat, the ball goes in the opposite direction with the same speed. The time of impact was 0.5 sec and the mass of the ball is 4 kg. Find (i) force exerted by the Indian player's bat on the ball (ii) impulse.
question_answer23) In a football match between England and Brazil, the Brazilian star Ronaldo strikes the ball towards the goal but an England defender exactly in front of him, kicks it back. The ball struck the defender's foot at the speed at 10 m/s and it rebounces back after kicking at 20m/s. The time of impact was 0.2 sec and mass of the ball is 1/2 kg. Find the average force exerted by the defender on the ball.
question_answer24) If action is always equal to the reaction, how does a cart pulled by a horse move?
question_answer25) Why is it difficult for a fireman to hold a hose which ejects large amounts of water at a high velocity?
question_answer26) Quicksand consists of very smooth and tiny grains of sand. What could happen if a man or heavy animal steps over a patch of such sand in a desert?
question_answer27) Rockets work on the principle of Newton's (a) First law (b) Second law (c) Third law (d) None of these
question_answer28) Swimming is possible on account of Newton's (a) First law (b) Second law (c) Third law (d) None of these
question_answer29) A car of mass 400 kg travelling at 72 kmph crashes into a truck of mass 4000 kg travelling at 9 kmph in the same direction. The car bounces back at a speed of 18 kmph. The speed of the truck after impact is____.
question_answer30) Two ice hockey players, suitably padded, collide directly with each other and immediately become entangled. One has a mass of 120 kg and is travelling at 2 m/s, while the other has a mass of 80 kg and is travelling at 4m/s towards the first player. In which direction and at what speed do they travel after they become entangled?
question_answer31) A bomb explodes into two pieces of equal mass. Show that the two pieces of the bomb fly in opposite directions.
question_answer32) A bullet of mass 100 g is fired from a gun of mass 20 kg with a velocity of \[\text{1}00\,\text{m}{{\text{s}}^{-\text{1}}}.\]Then find the velocity of recoil of the gun.
question_answer33) A truck weighing 2500 kg and moving with a velocity \[\text{28 m}{{\text{s}}^{\text{-1}}}\] collides with a stationary car weighing 300 kg. The truck and the car move together after the impact. Then find their common velocity.
question_answer34) The car A of mass 1500 kg travelling at 25 m/s collides with another car B of mass 1000 kg travelling at 15 m/s in the same direction. After collision the velocity of car A becomes 20 m/s. Find the velocity of car B after the collision.
question_answer35) If a string is inextensible the magnitude of acceleration of any number of masses connected through string is ______ (a) Always same (b) Always different (c) Sometime different (d) None of these
question_answer36) If a string is massless, the reaction in it is ??. everywhere. However, if a string has a mass tension at different points will be (a) Same, different (b) Different, same (c) Same, same (d) Different, different
question_answer37) Ranjith pulls a pair of identical 10.0 kg blocks across the floor with a rope that makes an angle of \[\text{3}0{}^\circ \] with respect to the horizontal. Draw the F.B.D of each block.
question_answer38) A 5.0 kg block is placed on top of a 10 kg block as shown below. A horizontal force of 45 N is applied to the 10 kg block, and the 5.0 kg block is tied to the wall. Draw a free-body diagram for each block.
question_answer39) A cylinder of weight w is resting on a V-groove as shown in the figure. Draw its free body diagram. (All the surfaces are frictionless).
question_answer40) Three blocks A, B and C are placed one over the other as shown in figure. Draw free body diagrams of all the three blocks. (All the surfaces are frictionless).
question_answer41) A block of mass 200 kg is set into motion on a frictionless horizontal surface with the help of frictionless and massless pulley and a rope system as shown in figure. Draw the free body diagrams of (a) pulley (b) block
question_answer42) A block of mass 2 kg placed on a long frictionless horizontal table is pulled horizontally by a constant force F. It is found to move 10 m in the first two seconds. Find the magnitude of F.
question_answer43) A car moving at 40 km/h is to be stopped by applying brakes in the next 4.0 m. If the car weighs 2000 kg, what average force must be applied on it?
question_answer44) In a TV picture tube electrons are ejected from the cathode with negligible speed and reach a velocity of \[\text{5}\times \text{l}{{0}^{\text{6}}}\]m/s in travelling one centimeter. Assuming straight line motion, find the constant force exerted on the electron. The mass of the electron is \[\text{9}.\text{1}\times \text{1}{{0}^{-\text{31}}}\] kg.
question_answer45) A particle of mass 50 g moves on a straight line. The variation of speed with time is shown in figure. Find the force acting on the particle t = 2, 4 and 6 seconds.
question_answer46) Raindrops of radius 1 mm and mass 4 mg are falling with a speed of 30 m/s on the head of a bald person. The drops splash on the head and come to rest. Assuming equivalently that the drops cover a distance equal to their radii on the head, estimate the force exerted by each drop on the head.
question_answer47) Two blocks of mass 4 kg and 2 kg are attached by an inextensible light string as shown in figure. Both the blocks are pulled vertically upwards by a force F = 120 N. Find, (a) The acceleration of the blocks (b) Tension in the string. (Take \[\text{g}=\text{1}0\text{m/}{{\text{s}}^{\text{2}}}\]).
question_answer48) A force \[\vec{F}=\vec{v}\times \vec{A}\] is exerted on a particle in addition to the force of gravity, where v is the velocity of the particle and A is a constant vector in the horizontal direction. With what minimum speed a particle of mass m be projected so that it continues to move undeflected with a constant velocity?
question_answer49) A block of mass 0.2 kg is suspended from the ceiling by a light string. A second block of mass 0.3 kg is suspended from the first block through another string. Find the tensions in the two strings. Take \[\text{g}=\text{1}0\text{ m}/{{\text{s}}^{\text{2}}}\].
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