Very Short Answer Type 1 Mark Questions

1. Define the conservative and non-conservative forces? Give example of each?2. A light body and a heavy body have same linear momentum. Which one hasgreater K.E? (Ans: Lighter body has more K.E.)3.If the momentum of the body is doubled by what percentage does its K.Echanges? (300%)4. A truck and a car are moving with the same K.E on a straight road. Their enginesare simultaneously switched off which one will stop at a lesser distance?(Truck)5. What happens to the P.E of a bubble when it rises up in water? (decrease)6. Define spring constant of a spring?7. What happens when a sphere collides head on elastically with a sphere of samemass initially at rest?8. Derive an expression for K.E of a body of mass m moving with a velocity v bycalculus method.9. After bullet is fired, gun recoils. Compare the K.E. of bullet and the gun.(K.E. of bullet K.E. of gun)10. In which type of collision there is maximum loss of energy?Very Short Answer Type 2 Marks Questions1. A bob is pulled sideway so that string becomes parallel to horizontal and released.Length of the pendulum is 2 m. If due to air resistance loss of energy is 10% what isthe speed with which the bob arrives the lowest point? (Ans : 6m/s)2. Find the work done if a particle moves from position r1 = (4i + 3j + 6k)m to aposition r 2 = (14i = 13j = 16k) under the effect of force, F = (4i + 4j - 4k)N?(Ans : 40J)3. 20 J work is required to stretch a spring through 0.1 m. Find the force constant ofthe spring. If the spring is stretched further through 0.1m calculate work done?(Ans : 4000 Nm1, 60 J)4. A pump on the ground floor of a building can pump up water to fill a tank ofvolume 30m3 in 15 min. If the tank is 40 m above the ground, how much electricpower is consumed by the pump? The efficiency of the pump is 30%.(Ans : 43.556 kW)5. Spring of a weighing machine is compressed by 1cm when a sand bag of mass0.1 kg is dropped on it from a height 0.25m. From what height should the sand bagbe dropped to cause a compression of 4cm? (Ans : 4m)6. Show that in an elastic one dimensional collision the velocity of approach beforecollision is equal to velocity of separation after collision?7. A spring is stretched by distance x by applying a force F. What will be the newforce required to stretch the spring by 3x? Calculate the work done in increasing theextension?8. Write the characteristics of the force during the elongation of a spring. Derive therelation for the P.E. stored when it is elongated by length. Draw the graphs to showthe variation of potential energy and force with elongation?9. How does a perfectly inelastic collision differ from perfectly elastic collision? Twoparticles of mass m1 and m2 having velocities u1 and u2 respectively make a head oncollision. Derive the relation for their final velocities?K.V. Silchar10510. In lifting a 10 kg weight to a height of 2m, 250 Joule of energy is spent. Calculatethe acceleration with which it was raised?(g=10m/s2) (Ans : 2.5m/s2)Short Answer Type 3 Marks Questions1. An electrical water pump of 80% efficiency is used to lift water up to a height of10m.Find mass of water which it could lift in 1hrour if the marked power was 500watt?2. A cycle is moving up the incline rising 1 in 100 with a const. velocity of 5m/sec.Find the instantaneous power developed by the cycle?3. Find % change in K.E of body when its momentum is increased by 50%.4. A light string passing over a light frictionless pulley is holding masses m and 2m atits either end. Find the velocity attained by the masses after 2 seconds.5. Derive an expression for the centripetal force experienced by a body performinguniform circular motion.6. Find the elevation of the outer tracks with respect to inner. So that the train couldsafely pass through the turn of radius 1km with a speed of 36km/hr. Separationbetween the tracks is 1.5m?7. A block of mass m is placed over a smooth wedge of inclination θ. With whathorizontal acceleration the wedge should be moved so that the block must remainstationery over it?8. Involving friction prove that pulling is easier than pushing if both are done at thesame angle.9. In vertical circular motion if velocity at the lowermost point is √(6rg) where find thetension in the string where speed is minimum. Given that mass of the block attachedto it is m?10. A bullet of mass m moving with velocity u penetrates a wooden block of mass Msuspended through a string from rigid support and comes to rest inside it. If length ofthe string is L find the angular deflection of the string.Long Answer Type 5 Marks Questions1. What is conservative force? Show that work done against conservative forces is astate function and not a path function. Also show that work done against it in acomplete cycle is zero?2. A body of man 10 kg moving with the velocity of 10m/s impinges the horizontalspring of spring constant 100 Nm-1 fixed at one end. Find the maximum compressionof the spring? Which type of mechanical energy conversion has occurred? Howdoes the answer in the first part changes when the body is moving on a roughsurface?3. Two blocks of different masses are attached to the two ends of a light stringpassing over the frictionless and light pully. Prove that the potential energy of thebodies lost during the motion of the blocks is equal to the gain in their kineticenergies?K.V. Silchar1064. A locomotive of mass m starts moving so that its velocity v is changing accordingto the law v √(as), where a is constant and s is distance covered. Find the total workdone by all the forces acting the locomotive during the first t seconds after thebeginning of motion?5. Derive an expression for the elastic potential energy of the stretched spring ofspring constant k. Find the % change in the elastic potential energy of spring if itslength is increased by 10%?Some Intellectual Stuff1. A body of mass m is placed on a rough horizontal surface having coefficient ofstatic friction μ with the body. Find the minimum force that must be applied on thebody so that it may start moving? Find the work done by this force in the horizontaldisplacement s of the body?2. Two blocks of same mass m are placed on a smooth horizontal surface with aspring of constant k attached between them. If one of the block is imparted ahorizontal velocity v by an impulsive force, find the maximum compression of thespring?3. A block of mass M is supported against a vertical wall by a spring of constant k. Abullet of mass m moving with horizontal velocity v0 gets embedded in the block andpushes it against the wall. Find the maximum compression of the spring?4. Prove that in case of oblique elastic collision of a moving body with a similar bodyat rest, the two bodies move off perpendicularly after collision?5. A chain of length L and mass M rests over a sphere of radius R (L one end fixed at the top of the sphere. Find the gravitational potential energy of thechain considering the center of the sphere as the zero level of the gravitationalpotential energy?