Question:
Breathing is the process that moves air in (inhaling) and out (exhaling) of the lungs.Breath is life as breathing provides 99% of energy to our bodies.
(a) What happens when we inhale ?
(b)Why a person with pulmonary disease has difficulty in breathing ?What message does it convey ?
(c) What is done to make a newborn have his first breath ?
Answer:
(a) Inhalation inflates the alveoli (balloon like structures in the lungs)-there are between 300 million and 400 million alveoli in each lung.
(b)The pulmonary disease(emphysema),most common in long term smokers,results from an enlargement of the alveoli as some are destroyed and others enlarge or combine.Normally,it would take twice the pressure to inflate a membrane with twice the radius.The enlarged alveoli provide less recoil on exhalation,and a person with emphysema has difficulty in breathing as well as reduced oxygen exchange.
Smoking results in painful existence leading to death and hence should be shunned at all costs.
(c)In a newbom baby,the alveoli are small and collapsed and must be inflated with initial inhalation.The traditional practice is to accomplish this are slaps on the baby’s bottom to make the newborn cry and inhale.
Motion
Q 1.
A farmer moves along the boundary of a square field of side 10 m in 40 s. What will be the magnitude of displacement of the farmer at the end of 2 minutes 20 seconds?
Q 2.
Derive graphically the equation of motion for position-velocity relation of a body moving with uniform acceleration.
Q 3.
A cyclist cycles for t second at a speed of 3 m/s and then for the same time at a speed of 5 m/s along a straight road due north. What is the average speed of the cyclist?
Q 4.
Calculate the greatest and the least pressure exerted by a metal block of size 20 cm x 8 cm x 5 cm and having a mass of 5 kg.
Q 5.
A body starts from rest.What is zero ?
Q 6.
When will you say a body is in (i) uniform acceleration? (ii) nonuniform acceleration?
Q 7.
A farmer moves along the boundary of a square field of side 10 m in 40 s.What will be the magnitude of displacement of the farmer at the end of 2 minutes 20 seconds ?
Q 8.
The mass of an empty 40 litre petrol tank of a vehicle is 8.0 kg.What will be its mass when filled completely with a fuel of density 700
Q 9.
Why is a slight blow on a cork of bottle fully filled with a liquid sufficient to break the bottle ?
Q 10.
Why does a person feel pain when he stands on a pile of gravel than when he stands on a bed of sand ?
Q 11.
Under what conditions(s) is the magnitude of average
Q 12.
Name the quantity that represents rate of change of velocity ?
Q 13.
What will be the initial velocity of an object under free fall?
Q 14.
A particle moves over three quarters of a circle of radius r.What is the magnitude of its displacement ?
Q 15.
Explain the terms : uniform motion and non-uniform motion with examples.
Q 16.
What is the relationship between the buoyant force on an object and the liquid displaced by it ?
Q 17.
The density of turpentine oil is
.What will be its relative density ?
Q 18.
Air is a fluid and our bodies displace air.As a result of this,a buoyant force is acting on each one of us.
(a)What is the approximate density of your body ?
(b) What is your approximate volume ?
(c) Estimate the magnitude of the buoyant force on you due to the air displaced.Consider your mass to be 75 kg.
(d)Does it mean that your weight is more than the scale reading ?
(Given density of air,pa =
)
Q 19.
Relative density of silver is 10.8.The density of water is
.What is the density of silver in SI units ?
Q 20.
Write the three equations of uniformly accelerated motion. Give the meaning of each symbol in them.
Q 21.
What is represented by the graphs in Fig.?
.
Q 22.
What does the slope of distance-time graph indicate?
Q 23.
An electric train is moving with a velocity of 120 km/h. How much distance will it move in 30 s ?
Q 24.
In addition to speed,what else should be known to predict the position of a moving body from a given starting point ?
Q 25.
Name the terms represented by various symbols in the equation, v = u + at.
Q 26.
What is the relation between true weight,apparent weight and the loss in weight of a body immersed in a fluid ? Give some practical applications of Archimedes’Principle.
Q 27.
Why are sleepers used below the rails ?
Q 28.
What does the path of an object look like when it is in uniform motion?
Q 29.
Fill in the blanks :
The rate of change of velocity of a moving body with time is called ______.
Q 30.
What can you say about the motion of an object whose distance-time graph is a straight line parallel to the time axis ?
Q 31.
What is meant by scalars and vectors?
Q 32.
Use graphical method to derive the relation
-
= 2 as,where the symbols have their usual meanings.
Q 33.
The mass of a solid rectangular block of iron is 23.6 g and its dimensions are 2.1 cm x 1.2 cm x 1.1 cm.Calculate the density of iron.
Q 34.
A car travels along a straight line for first half time with speed 40 km/h and the second half time with speed 60 km/h. Find the average speed of the car.
Q 35.
What are the values of distance travelled and displacement in covering 10 m from P to Q and coming back ?
Q 36.
Why is it easier to swim in sea water than in river water ?
Q 37.
What can you calculate from speed-time graph of a body ?
Q 38.
What is thrust ?How is it related to pressure ? Give their units.
Q 39.
A ship is moving at a speed of 56 km/h.One second later,it is moving at 58 km/h.What is its acceleration ?
Q 40.
A weather forecasting plastic balloon of volume
contains hydrogen of density
.The mass of the empty balloon is 7.15 kg.Calcuiate (a) the mass or 'hydrogen in the balloon (b) Tne mass of balloon filled with hydrogen.
Q 41.
Fig (below) shows the distance-time graph of three objects A,B and C. Study the graph and answer the following questions:
(a) Which of the three is travelling the fastest?
(b) Are all three ever at the same point on the road?
(c) How far has C travelled when B passes A?
(d) How far has B travelled by the time it passes C?
Q 42.
When will you say a body is in (») uniform acceleration ? (ii) non-uniform acceleration ?
Q 43.
An artificial satellite is moving in a circular orbit of radius 42250 km. Calculate its speed if it takes 24 hours to revolve around the Earth.
Q 44.
What conclusion do you draw when displacement-time graph of a body is as shown in Fig.?
Q 45.
A block of wood is kept on a table top.The mass of the wooden block is 5 kg and its dimensions are 40 cm x 20 cm x 10 cm.Find the pressure exerted by the wooden block on the table top if it is made to lie on the table with its sides of dimensions (a) 20 cm x 10 cm (b) 40 cm x 20 cm. Given g =
.
Q 46.
A solid body of mass
kg and volume
is put in water.Will the body float or sink ?
Q 47.
A particle moves along the x axis from A to B. Which Of the following values of the initial and final coordinates, which results in a negative displacement?
(a) A = 4m, B = 6m
(b) A = −4m, B = −2m
(c) A = −4m, B = −8m
(d) A = −4m, B = 2m
Q 48.
Distinguish between speed and velocity.
Q 49.
A racing car has a uniform acceleration of 4 m s–2.
What distance will it cover in 10 s after start?
Q 50.
A scalar quantity has ?
(a) magnitude only
(b) direction only
(c) both direction and magnitude
(d) none of these
