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Explain why food can be cooked rapidly by boiling in salt water rather than pure water
If P = 3i + 2j and Q = 4i + 3j, Find Q - P
A magnetic field B= 0.6T is directed upward through a circular loop of diameter 7 cm and 500 turns. The loop is initially horizontal, so it is perpendicular to the magnetic field. It rotates through a horizontal axis so that the plane of the loop is at 74° with the horizontal axis within 1 second. What is the magnitude of the induced emf?
- 0°
- 90°
- 60°
21. The body, which is attracted by a constant force F = 20N, moves at a constant speed, on a horizontal surface. In these conditions we can say: A) the resultant force has the value 20N B) the friction force has the value 20N C) the friction force is zero D) no other forces act on the body
22. A body weighing 1kg is thrown vertically upwards at a speed of 10m / s. The potential energy at the highest point will be: A) 1000 B) 500 C) 250 D) OJ
23. A car moving at a speed of 72km / h on a straight road, brakes by moving with acceleration a = -2m / s² until it stops. a) After how long will the speed of the car be halved? b) After how long will the car stop? C) How far is it from the moment of braking until it stops?
24. On a block of ice, located on a horizontal plane smooth at rest, acts a constant horizontal force of magnitude 40N for 5 sec. (f = 0). As a result of the action of force the block moves 100 m. What is the mass of the ice block?
A distant quasar is moving away from the earth at a speed u. An astronomer is searching for a certain spectral line in the light from the quasar. The line emmited by atomic hydrogen is observed using hydrogen discharge tubes on earth to have a wavelength of 121.6nm. The astronomer finds the hydrogen spectral lines emmitted by the quasar at wavelength of 460.9. Assuming the quasar to be moving radially away from earth what is the speed relative to the earth? Interpet your answer
Using a graphical ray diagram derive the thin -lens equation 1/u+1/v=1/f. Where u is the object distance v, the image distance and f the focal length
