Selina solutions concise physics class 6 icse Solutions for Chapter 3 force

Q1) Write true or false for each statement :

(a) The frictional force acts in the direction of motion of the body.

(b) The unit of weight is kilogram.

(c) A force can change the direction of motion of a moving body.

(d) A force increases the mass of the body when applied on it.

(e) The force of friction is always disadvantageous.

(f) The sliding friction is more than the rolling friction.

(g) Liquids offer more friction than the gases.

(h) A wet oily road offers more friction than a dry rough road.

Q2 Fill in the blanks

(a) Force is applied as ______or ______ .

(b) On squeezing a gum tube, its ______ changes.

(c) On pulling a string, its ______ increases.

(d) A moving football when kicked, its ______ __________ changes.

(e) On applying brakes on a moving car, its speed ________.

(f) We use ball bearings to ______ friction.

(g) Friction ______ the motion.

(h) Lubricants are used to _________ friction.

(i) _________ causes wear and tear of moving parts of a machine.

Q3) Match the following columns :

Q4) Select the correct alternative :

(a) A body falls downwards because of

1. Electrical force

2. Gravitational force

3. Mechanical force

4. Magnetic force

(b) A force does not change

1. Mass

2. Length

3. Shape

4. State of motion

(c) A force to be expressed correctly requires

1. Only the magnitude

2. Only the direction

3. Both the magnitude and direction

4. None of the above.

(d) Friction

1. Promotes motion

2. Opposes motion

3. Acts in the direction of motion

4. Is always a nuisance

(e) Friction is reduced by

1. Making the surfaces wet

2. Making the surfaces dry

3. Making the surfaces rough

4. Sprinkling sand on the surface.

(f) Friction

1. Causes wear and tear

2. Produces heat

3. Stops a moving body

4. Has all the above disadvantages

(g) Friction is increased if

1. Oil is sprayed

2. The surfaces are made wet

3. The surfaces are made dry

4. The surfaces are polished

Q1) Name the term used for the push or pull ?

Q2) Give one example each of a force as

1. a push

2. as pull

3. a stretch and

4. a squeeze

Q3) Explain the meaning of the term force.

Q4) What effect can a force have on a stationary body ?

Q5) What effects can a force have on a moving body ?

Q6) What effect can a force produce on a body which is not allowed to move ?

Q7) Give one example each to indicate that the application of a force :

1. produces motion

2. stops motion

3. slows down motion

4. changes the direction of motion

5. deforms a body

Q8) State the effect produced by a force in the following cases :

(a) The sling of a rubber catapult is stretched.

(b) A man pushes a heavy cart.

(c) A player uses his stick to deflect the ball.

(d) A cyclist applies brakes.

(e) A spring is compressed.

Q9) Name the two kinds of forces in nature.

Q10) Name the type of force which acts in the following cases :

(a) A coolie lifts a luggage

(b) A bicycle comes to rest slowly when the cyclist stops pedalling

(c) A stone falls from a roof

(d) A comb rubbed with silk attracts the bits of paper

(e) A string hangs with a load

(f) A horse moves a cart

(g) A magnet attracts an iron pin

(h) A boy opens the door

(i) An apple falls from a tree

(j) A man rows a boat

Q11) What do you mean by the gravitational force ? Give an example to illustrate it .

Q12) Define the term “weight of a body”.

Q13) What do you understand by the term friction ?

Q14) Give an example to illustrate the existence of force of friction.

Q15) What is the cause of friction ?

Q16) State two factors which directly affect the force of friction .

Q17) In which case will there be more friction between the truck and the road : when the truck is empty or when it is loaded ?

Q18) Which offers more friction on a body : a glass surface or a wooden surface ?

Q19) Name the three kinds of friction.

Q20) List three disadvantages of friction .

Q21) When you apply the brakes, the bicycle stops and the rim of the wheel becomes hot. Explain the reason.

Q22) The eraser gets smaller and smaller as you use it more and more. Explain the reason.

Q23) List three ways of reducing friction.

Q24) It is difficult to open an inkpot with greasy or oily hands. Explain.

Q25) It is difficult to walk on a wet road. Explain.

Q26) Give three examples to illustrate that friction is a necessary evil.

Q27) Define

1. Static friction

2. sliding friction and

3. rolling friction