Question

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1. a) Write the advantage of using mercury as a thermomertic fluid. (4)
b) Difference between Beam balance and electronic balance. (4)
c) Define Parallax error. (2)
2.a) Write short notes on:- (4)
i) Measurement. ii) Temperature
b) Write the steps to be followed while measuring a length using a ruler. (4)
c) What is the role of kink in a clinical thermometer? (2)
3.a) Write the advantage of friction.(4)
b) Write the types of friction. (4)
c) Define collision force. (2)
4.a) Write the 4 methods of reducing friction. (4)
b) Write the methods of increasing friction. (4)
c) write 2 disadvantage of friction. (2)
5.a) Give the names of different types of non-contact force. (4)
b) Explain Clinical thermometer. (4)
c) Write Short notes on:- (2)
i) Temperature.
ii) Kinetic friction.​

Answer 1

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(1.) a) Advantages of mercury as a thermometric liquid. -It is a good conductor of heat and therefore the whole liquid reaches the temperature of the surroundings quickly. -It does not wet (cling to the sides of) the tube. -It expands uniformly (linear expansion) and responds quickly to temperature changes, hence is seen

b) When the two objects balance at the exact same level, they have equilibrium, or the same mass. Electronic scales use electrical resistance to determine the weight of an object. ... Balance beam scales work on the theory of mass, while electronic scales measure weight.

2.) a) 1)Measurement is the assignment of a number to a characteristic of an object or event, which can be compared with other objects or events. This system reduces all physical measurements to a mathematical combination of seven base units.

2) Temperature is a physical quantity that expresses hot and cold. It is the manifestation of thermal energy, present in all matter, which is the source of the occurrence of heat, a flow of energy, when a body is in contact with another that is colder. Temperature is measured with a thermometer.

b) Care should be taken to keep the ruler along the length of the object. If the edge of the ruler is worn out or broken, the measurement should be started from any other mark that is fully clear. Eyes should be exactly above the point where the measurement is to be taken.

c) Kink plays an important role in thermometers. It prevents the rapid falling of the mercury back into the bulb of the thermometer. Hence we can measure the temperature of the body accurately and conveniently even if the thermometer is taken out from the body.

3.) a) Advantages of Friction:

• Friction is responsible for many types of motion.
• It helps us walk on the ground.
• Brakes in a car make use of friction to stop the car.
• Asteroids are burnt in the atmosphere before reaching Earth due to friction.
• It helps in the generation of heat when we rub our hands.

b). Static, sliding, and rolling friction occur between solid surfaces. ...

Fluid friction occurs in fluids, which are liquids or gases.

c) In a collision, there is a force on both objects that causes an acceleration of both objects; the forces are equal in magnitude and opposite in direction. For collisions between equal-mass objects, each object experiences the same acceleration.

(4.)

Answer 2

It is an optical illusion which is responsible for the appearance of the water layer at short distances in a desert or on the road. Mirage is an example of total internal reflection which occurs due to atmospheric refraction.