Question:
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 ?
Answer:
In Fig.,ABCD is a square field of side 10 m.
Time for one round = 40 s,
Total time = 2 min 20 s = (2 x 60 + 20) s = 140 s
Number of rounds completed = = 3.5
If farmer starts from A, he will complete 3 rounds (A→B → C→ D →A) at A.In the last 0.5 round starting from A, he will finish at C.
Displacement = AC,where AC =
=yJjO2 +102 = I0√2m
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.
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 4.
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 5.
Why does a person feel pain when he stands on a pile of gravel than when he stands on a bed of sand ?
Q 6.
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 7.
A body starts from rest.What is zero ?
Q 8.
Why is a slight blow on a cork of bottle fully filled with a liquid sufficient to break the bottle ?
Q 9.
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 10.
When will you say a body is in (i) uniform acceleration? (ii) nonuniform acceleration?
Q 11.
Explain the terms : uniform motion and non-uniform motion with examples.
Q 12.
What is the relationship between the buoyant force on an object and the liquid displaced by it ?
Q 13.
An electric train is moving with a velocity of 120 km/h. How much distance will it move in 30 s ?
Q 14.
Name the quantity that represents rate of change of velocity ?
Q 15.
A particle moves over three quarters of a circle of radius r.What is the magnitude of its displacement ?
Q 16.
Under what conditions(s) is the magnitude of average
Q 17.
In addition to speed,what else should be known to predict the position of a moving body from a given starting point ?
Q 18.
What is represented by the graphs in Fig.?
.
Q 19.
Write the three equations of uniformly accelerated motion. Give the meaning of each symbol in them.
Q 20.
The density of turpentine oil is
.What will be its relative density ?
Q 21.
What will be the initial velocity of an object under free fall?
Q 22.
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 23.
Relative density of silver is 10.8.The density of water is
.What is the density of silver in SI units ?
Q 24.
What does the path of an object look like when it is in uniform motion?
Q 25.
Name the terms represented by various symbols in the equation, v = u + at.
Q 26.
An object weighs 9.8 N in air and 9.0 N when fully immersed in water.How much is the buoyant force on the object ?
Q 27.
Fill in the blanks :
The rate of change of velocity of a moving body with time is called ______.
Q 28.
What can you say about the motion of an object whose distance-time graph is a straight line parallel to the time axis ?
Q 29.
What does the slope of distance-time graph indicate?
Q 30.
Fill in the blanks :
If the position of an object does not change with time, it is said to be at _____.
Q 31.
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 32.
What are the values of distance travelled and displacement in covering 10 m from P to Q and coming back ?
Q 33.
Why Is it difficult to hold a school bag having strap made of thin and strong string ?
Q 34.
Why is it easier to swim in sea water than in river water ?
Q 35.
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 36.
A scalar quantity has ?
(a) magnitude only
(b) direction only
(c) both direction and magnitude
(d) none of these
Q 37.
Use graphical method to derive the relation
-
= 2 as,where the symbols have their usual meanings.
Q 38.
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 39.
What is meant by scalars and vectors?
Q 40.
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 41.
Why are sleepers used below the rails ?
Q 42.
What can you calculate from speed-time graph of a body ?
Q 43.
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 44.
Draw speed-time graph for a body (i) at rest (ii) in uniform motion (iii) in uniformly accelerated motion.Discuss the results briefly.
Q 45.
What is thrust ?How is it related to pressure ? Give their units.
Q 46.
An object has moved through a distance. Can it have zero displacement? If yes, support your answer with an example.
Q 47.
What do you mean by a body in rest?
Q 48.
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 49.
Is distance a vector quantity ?
Q 50.
Define pressure.What is its unit ?
