Answer any two (2) questions under this paper 1. a) What is frictional force? b) Mention three (3) benefits of frictional force. c) State four (4) effects of frictional force. d) List four (4) ways of reducing friction 2. a) Differentiate between heat and temperature. b) Explain the effect of heat on temperature change. c) Mention four (4) types of thermometers and give the use of each. d) Make a list of three (3) cold objects and three (3) hot objects. 3. a) What is an electrical circuit? b) List the two (2) types of circuit and explain them. c) Mention six (6) components of an electrical circuit. d) Give the function of each of the components you have mentioned in question .3. b) above. 4. a) List four (4) dangers of misusing electrical energy. b) Mention six (6) sources of electrical energy. c) Give four ways electricity can be preserved. d) State four appliances that use too electricity
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okay I am answering 1 and 2 i.e 1.a,b,c,d and 2.a,b,c,d
1.a)Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: Dry friction is a force that opposes the relative lateral motion of two solid surfaces in contact.
b)Advantages of friction:
- Friction enables us to walk freely.
- It helps to support ladder against wall.
- It becomes possible to transfer one form of energy to another
c)effects of friction
- It produces heat,
- that helps in heating parts of any object or to warm ourselves.
- It also causes loss in power. It produces noise during any kind of operation. It's because of friction that we're able to walk, run, play, etc.
d)four ways are:
- lubricants
- ball bearings
- Make the surfaces smoother.
- stream lining
2.a)Heat describes the transfer of thermal energy between molecules within a system and is measured in Joules. Heat measures how energy moves or flows. ... Temperature describes the average kinetic energy of molecules within a material or system and is measured in Celsius (°C), Kelvin(K), Fahrenheit (°F), or Rankine (R).
b)Temperature Increase
When heat energy is added to a substance, this results in an increase in the kinetic energy of its particles, that is, the particles move at higher speeds. Since temperature is a measure of the average kinetic energy, the temperature increases.
c)A thermometer is a device that is used to measure the temperature of a body. Common types of thermometers are Medical thermometers, Infrared thermometers, Mercury thermometers, thermocouple thermometers, laboratory thermometers, Bimetallic strip thermometers, Pyrometers, etc.
d)Cold objects:-
- AC
- Refrigerator
- Ice
2.Hot objects
- Molten iron
- steam
- burners
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Answer:
1.FORCE CHANGES DIRECTION OF MOTION - EXAMPLE
When a ball hits against a wall, it bounces back in the opposite direction. So the force exerted by the wall on the ball changes its direction of motion.
FORCE CHANGES SHAPE OF OBJECT - EXAMPLE
When a hammer strikes a hot rod, the rod bends. The force exerted by the hammer on the rod changes the shape of the rod.
EXAMPLES FOR EFFECT OF FORCE - EXAMPLE
Force may bring the following change:
1) Can change the state of an object(rest to motion/ motion to rest):For example, pushing a heavy stone in order to move it.
2) May change the speed of an object if it is already moving.For example,catching a ball hit by a batsman.
3) May change the direction of motion of an object.For example,footballer kicks a moving ball to change its direction.
4) May bring about a change in the shape of an object.For example, blowing air in balloon.
5) May cause some or all of these effects.
2. Contact forces Non-contact forces
These are forces which need a physical touch on the object to act upon it. These are forces which do not need a physical contact to act on an object.
These may or may not be natural forces. These are natural forces
They can not work from a distance. They can work from a distance as well.
Its various types are applied force, normal force, tension frictional force its various types are magnetic force electrostatic force,gravitational force
Examples player kiicking a ball game of tug of war rolling ball stops itself horse pulling a cart etc, Examples: magnet attracting iron nails, mango falling from tree, charged plastic ruler attracts bits of dry - paper etc.
3.All objects have a tendency to fall towards the earth when thrown up due to the influence of gravity. The gravitational force acts upon the body and it tends to fall towards the earth. The force of attraction between two bodies that has mass.
4.The mass of an object is a measure of the object's inertial property, or the amount of matter it contains. The weight of an object is a measure of the force exerted on the object by gravity, or the force needed to support it. The pull of gravity on the earth gives an object a downward acceleration of about 9.8 m/s2.
5.Friction depends on the nature of surfaces in contact. For a given pair of surfaces, friction depends upon the state of smoothness of those surfaces. The force of friction is greater if a rough surface is involved. Friction is caused by the irregularities on the two surfaces in contact.
6. The main disadvantage of friction is that it produces heat in various parts of machines. In this way some useful energy is wasted as heat energy. ... Due to friction, engines of automobiles consume more fuel which is a money loss.
7. The use of bearing surfaces which are sacrificial by themselves, such as low shaving materials, is an example. There are many ways to minimize friction. Replace the rolling element rolling tension with rolling element rolling element rolling bearing.Friction can be significantly reduced if either the object or the surface is smooth and straight or the opposite sometimes, tires in cars are specially made to fight friction when needed and reduce it (some cars increase friction but that's a whole different thing), also when planes are speeding up on the lane they need to minimize friction to an extent they will be going extremely fast, fast enough to take off so engineers and workers always make sure to make lanes organized and smooth without even a small rock on them and the wheels of the plane rather smooth to decrease friction the best they can. Sometimes friction goes against the object and doesn't let it move smoothly (you get a ring stuck on your finger, the door knob is moving more rustly, doors and such things are creaking more), then that requires some oily and and with a consistency to make the surface smooth and reduce the friction for smoother movement.
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This is all I have, hope it helps
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