| Previous Year Questions of March Examinations from 2010 to 2020 |
| Chapter Name: LAWS OF MOTION |
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A passenger of mass 30 kg is standing in a lift which is moving vertically downwards with an acceleration of 1.8 m/s2
a) Will the passenger experience decease or an increase in his weight/ Explain? b) What will be the effect if the cable is cut and the lift falls freely? |
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There are different types of forces in nature. We learnt their effects and applications. Give the exact reasons for the following. a) Why can’t a horse pull a cart in empty space? b) Why are passengers thrown forward when a speeding bus stops suddenly? c) Why does a satellite revolve around the earth in a circular path ? d) Why is it easy to lift a heavy stone in a water ? |
| A block of mass ‘M’ is suspended by a light cord ‘C’ from the ceiling and another strong cord ‘D’ is attached to the bottom of the block as shown. The cord ‘D’ is pulled by a force ‘F’. Which of these cords will break, if a) The force is increased steadily? b) The force is increased suddenly? |
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Raising the outer edge of a curved road a little above the inner edge is called banking of curves. a) Derive an expression for the safe speed with which a car can negotiate a banked road by taking into account the friction between the tyres and the road. b) A machine gun fires bullets of mass 40 g each with a speed of 1200 ms-1 . The person can hold the gun with a maximum force of 144 N. What is the maximum number of bullets that can be fired per second from the gun? |
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According to Newton’s law of motion, the force depends on the rate of change of momentum. a) State whether the force is external or internal? Justify your answer. b) What happens to the linear momentum when the force is absent? c) The motion of a particle of mass m is described y= ut + ½ at2 . find the force acting on the particle. d) Why is it more difficult to rotate a stone by tying it to a longer string than a shorter string? |
Match the following.
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According to Newton’s law of motion, the force depends on the rate of change of momentum. a) Name the law that helps to measure force. b) Using the above law, deduce an expression for force. c) A man jumping out of a moving bus falls with his head forward. What should he do in order to land safely. |
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We are familiar with Newton’s laws of motion. a) State Newton’s second law of motion. b) Using the above law, explain: i. Impulse – momentum principle ii. Law of conservation of linear momentum c) A circular racetrack of radius 300 m is banked at an angle of 150 . The coefficient of friction between the wheels of a race car and the road is 0.2. Find: i. The optimum speed of the race car to avoid wear and tear on its tyres. ii. Maximum permissible speed to avoid slipping. |
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a) State whether the following statements are True or False. Correct the statements if false. i. A spring balance gives the mass of a body while a common balance gives its weight. ii. If the same force is applied on two bodies of different masses for the same time, then the change in momentum of two bodies is the same. b) State Newton’s second law and arrive at the equation of force. c) A motorcycle and a bus are moving with same momentum. Which of them has greater kinetic energy? Justify. |
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When a horse suddenly starts moving, the rider fails backward. a) Name and state the law used to explain the above situation. b) State the law of conservation of linear momentum and prove it on the basis of second law of motion. c) State true or false. An iron ball and a wooden ball of the same radius are released from a height in vacuum; the iron ball will reach the ground first. |
| The schematic diagram of the ciroular motion of ron a banked road is shown in the figure a) If the centripetal force is provided by the horizontal components of “N” and “f “, arrive at an expression for maximum safe speed. b) The optimum speed of a car on a banked road avoid wear and tear on its tyres is given by ................... i) sqrt(Rg Tan θ) ii) sqrt(Rg Cot θ) iii) sqrt(Rg Sin θ) iv) sqrt(Rg Cos θ) |
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A gun moves backward when a shot is fired from it a) Choose the correct statement i) The momentum of the gun is greater than that of the shot ii) The momentum acquired by the gun and shot have the same magnitude iii) Gun and shot acquire the same amount of kinetic energy b) A shell of mass 0.020 kg is fired by a gun of mass 100 kg. If the muzzle speed of the shell is 80 m/s, what is the recoil speed of the gun? |
| a) What is the condition for the equilibrium of concurrent forces? b) A mass of 6 kg is suspended by a rope of length 2 m from the ceiling. A force of 50 N in the horizontal direction is applied at the midpoint P of the rope, as shown. What is the angle, the rope makes with the vertical in equilibrium? (Take g = 10 m/s2) Neglect the mass of the rope c) What will be the angle made by the rope with the vertical if its length is doubled? |
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A light bullet is fired from a heavy gun a) Choose the CORRECT i) Speed of the gun and the bullet are equal ii) Momenta of the bullet and gun are equal in magnitude and opposite in direction iii) Momenta of the gun and bullet are equal in magnitude and are in the same direction iv) Velocity of gun and bullet are equal b) By using a suitable conservation law in physics, prove your above answer |
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Free fall is a uniformly accelerated motion a) Draw the velocity - time graph of free fall b) Ball is thrown vertically upwards with a velocity of 20 ms-1 from the top of a building. The height of the point from where the ball is thrown is 25.0 m from the ground i) How high will the ball rise? ii) How long will it be before the ball hits the ground? |
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Static friction opposes impending motion a) Write the mathematical equation connecting the limiting value of static friction with normal reaction b) Choose the CORRECT statement : i) Both kinetic friction and static friction are independent of the area of contact ii) Kinetic friction depends on area of contact, but static friction do not iii) Static friction depends on area of contact but kinetic friction do not iv) Both kinetic friction and static friction depend of the area of contact c) A mass rests on a horizontal plane. The plane is gradually inclined until at an angle θ with the horizontal, the mass just begins to slide. Show that the coefficient of static friction between the block and the surface is equal to Tanθ |
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Newton’s first law of motion describes the ........... (a) Energy (b) Work (c) Inertia (d) momentum |
| State the law of conservation of linear momentum. |
| Circular motion of a car on a banked road is shown in figure (a) Write the name of forces A, B, C, D in the figure. (b) Write the equation which equate forces on the car along horizontal and vertical direction. (c) State the law of static friction. |
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| State Newton’s Universal Law of Gravitation |
| State Newton’s second law of motion and write the equation of force |
| What is the difference between elastic and inelastic collisions ? Derive an expression for loss in kinetic energy on completely inelastic collision of two bodies in one dimensional motion |
