ECAT 2017 Physics Potion

ECAT 2017 Physics Portion

1. In an experiment, the length of a steel rod is to be measured. For this purpose, a student finds two different devices in the lab. Device A can measure the length with an absolute uncertainty of 0.5cm while device B can make the same measurement with an absolute uncertainty of 0.05cm. For precise measurement, the student should ;
   

2. Which of the following expressions could be a valid expression for velocity of ocean waves in terms of the density of sea water (ρ) , the depth of the ocean (h) , the wavelength (λ) and the acceleration of free fall (g) ;
   

3. Two forces of magnitude and act at a point. Which of the following cannot be the magnitude of the resultant force?
   

4. Three uniform bricks, each of length L, are stacked as shown in the figure below.
   
   
   Which of the following can be a valid value of x, if the resultant system is in equilibrium?
   

5. An old communications satellite orbiting at a radius r₁ is replaced by a new satellite at an orbit of radius r₂. The new satellite has twice the mass of the first satellite and each of the satellite has an orbit time of 24 hours. The ratio is r₂  ⁄  r₁;
   

6. A solar panel delivers 100 watts for one minute. How much energy does it deliver during the period?
   
   
   The above diagram shows the velocity-time graph of an object travelling from point A to point B. Answer the next questions using the above graph.

7. The maximum acceleration of the object during the journey is ;
   

8. The total distance covered during the journey is:
   

9. A stone, thrown at an angle to the horizontal in a gravitational field, following a parabolic path, PQRST in the absence of air resistance. These points denote the position of the stone after successive equal time intervals. T is the highest point reached. The displacements PQ,QR, RS and ST:
   

10. When a bus is at rest, a pendulum bob hanging from the celling inside the bus is just above a certain mark on the floor. When the bus moves in a straight line at a constant speed of 120km/hr. on the motorway, the pendulum bob:
    

11. A tuning fork P produces 12 beats per second with another tuning fork Q. If the frequency of Q is 200 Hz, the frequency of P is:
    

12. The following graph shows the variation of force F on a body with time t.
    
    
    The area under the graph represents:
    

13. A particle P moving with kinetic energy E and momentum ρ makes a head-on collision with an identical particle Q which is initially at rest. Both particles stick together. Which one of the following rows correctly represents the kinetic energy and magnitude of the momentum after the collision?
    

14. A stone of mass m is thrown vertically upwards with velocity v. Neglecting air resistance, which of the following statements is correct?
    

15. A steel ball held a short distance h above the surface of a liquid, in a deep tank, is released. Which one of the following does NOT affect the terminal velocity of the ball in the liquid?
    

16. Two skaters of equal mass, facing each other and holding hands with arms outstretched, is spinning at angular velocity w about a vertical axis midway between them. If they move close together so that they halve their separation, their new angular velocity is:
    

17. A person stands on a weighing scale in a lift going upwards with constant velocity. If the weight of the person under normal circumstances is W, the weight shown by the weighing scale in the lift will be?
    

18. A pendulum is oscillating in simple harmonic motion. Which of the following graphs correctly shows the variation of its acceleration α with respect to the displacement x from the Centre of its path?
    

19. A simple pendulum with length l is known to oscillate with a period T seconds. If the length of the pendulum is increased to 2l and the maximum displacement of the pendulum remains the same, the total energy of the system will:
    

20. Two copper wires of the lengths l and 2l are stretched by a force F. If the cross sectional area of wire of length l is A, what is the cross sectional area of the wire of length 2l if the extension in both wires is same?
    

21. The frequency of the fundamental mode of transverse vibration of a stretched wire 1000 mm long is 250 Hz. When the wire is shortened to 500 mm at the same tension, what is the fundamental frequency?
    

22. Coherent monochromatic light illuminates two narrow parallel slits and the interference pattern which results is observed on a screen some distance beyond the slits. Which of the following modifications will increase the separation between the dark lines of the interference pattern?
    

23. A ray of the light is incident on a glass-air boundary for which the critical angle is C. If the speed of light in the glass is known to be half the speed of the light in vacuum, the critical angle C is:
    

24. The temperature of 1 kg of hydrogen gas is the same as that of 1 kg of helium gas if:
    

25. A wire loop is placed in between the poles of the magnet as shown in the figure below.
    
    
    
    If the wire loop is rotated clockwise around the axis, which of the following statements regarding the instantaneous current in the PQ segment is correct?
    

26. In the direction indicated by an electric field line:
    

27. A source initially contains N_o nuclei of a radioactive nuclide. How many of these nuclei have decayed after a time interval of three half-lives?
    

28. The electrons in a cathode-ray tube are accelerated from cathode to anode by a potential difference of 2000 V. If this potential difference is increased to 8000 V, the electrons will arrive at the anode with:
    

29. Three similar light bulbs are connected to a constant voltage DC supply as shown in the diagram. Each bulb operates at normal brightness and an ammeter of negligible resistance registers a steady current.
    
    
    One more similar light bulb is connected in parallel to the three bulbs. What happens to the ammeter reading and the brightness of the four bulbs?
    

30. The truth table shown in the figure if implemented by:
    

ANSWERS

For more Info. Please write in Comment. Thanks.