Question:
Orbit of an artificial satellite at distance 42260 km from earth is circular. It completes one revolution around the earth in 24 hours. Calculate its linear speed.
Answer:
: Linear speed in uniform circular motion = Circumference ÷ time = 2πr ÷ t
Given, 42,260 km, t = 24 h
⇒ v = 2 ✕ 3.14 ✕ 42260 ÷ 24 = 11058.03 km/hr
Motion
Q 1.
The equation S = ut + ½at2 gives information as
(a) velocity is a function of time.
(b) velocity is a function of position.
(c) Position is a function of time.
(d) Position is function of velocity and time.
Q 2.
Fill in the blanks :
The rate of change of velocity of a moving body with time is called ______.
Q 3.
Are motion and rest absolute or relative? Explain with an example.
Q 4.
What do you mean by a body in rest?
Q 5.
Under what condition(s) is the magnitude of average velocity of an object equal to its average speed?
Q 6.
Which of the following is true for displacement?
(a) It cannot be zero.
(b) Its magnitude is greater than the distance travelled by the object.
Q 7.
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 8.
A bus decreases its speed from 80 km/h to 60 km/h in 5 s. Find the acceleration of the bus.
Q 9.
A racing car has a uniform acceleration of 4 m s–2.
What distance will it cover in 10 s after start?
Q 10.
What is the average velocity over the “round trip” of an object that is thrown straight up from the ground and falls straight back down to the ground?
Q 11.
What does the slope of distance-time graph indicate?
Q 12.
When will you say a body is in (i) uniform acceleration? (ii) nonuniform acceleration?
Q 13.
Which of the following is true for displacement ?
(a) It cannot be zero.
(b) Its magnitude is greater than the distance travelled by the object.
Q 14.
(a)
Which human virtue was at stake when Archimedes came out with his principle while bathing in a tub ?
(b) Briefly discuss three cases where Archimedes Principle is at work.
Q 15.
Distinguish between speed and velocity.
Q 16.
Calculate the mass of air enclosed in a room of length,breadth and height equal to 5 m, 3 m and 4 m respectively.Density of air =
.
Q 17.
What is locomotion ?
Q 18.
Derive graphically the equation of motion for position-velocity relation of a body moving with uniform acceleration.
Q 19.
The following is the distancc-time table of a moving car.
(a) Use a graph paper to plot the distance travelled by the car versus the time.
(b) When was the car travelling at the greatest speed ?
(c) What is the average speed of the car ?
(d) What is the speed between 11.25 am and 11-40 am ?
(e) During a part of the journey, the car was forced to slow down to 12 km/h.At what distance did this
| Time | Distance |
|---|
10.05 am
10.25 am
10.40 am
10.50 am
11.00 am
11.10 am
11.25 am
11.40 am | 0 km
5 km
12km
22 km
26 km
28 km
38 km
42 km |
Q 20.
A motor cycle moving with a speed of 5 m/s is subjected to an acceleration of 0.2
.Calculate the speed of the motor cycle after 10 second,and the distance travelled in this time.
Q 21.
What is the acceleration of a body moving with uniform velocity ?
Q 22.
Using velocity time graph,establish the relation s = ut +
,where the symbols have their usual meanings.
Q 23.
Why do you feel lighter when you swim ?
Q 24.
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 ?
Q 25.
Define the term uniform acceleration.Give one example of uniformly accelerated motion.
Q 26.
A stone tied to one end of a string is rotated in a circle.Explain what happens when the stone is released.
Q 27.
A metallic sphere of radius 2.0 cm is completely dipped in water.Find the force of buoyancy on it.
Q 28.
A body of 2.0 kg floats in a liquid.What is the buoyant force on the body ?
Q 29.
What is Archimedes’ Principle ? How can it be experimentally verified ?
Q 30.
A particle is moving in a circle of diameter 5 m. Calculate the distance covered and the displacement when it completes 3 revolutions.
Q 31.
Is displacement a scalar quantity ?
Q 32.
Explain what is meant by uniform circular motion.Give at least three examples.
Q 33.
Human corpse always floats on the surface of water,but the head always stays within water.Why ?
Q 34.
A bus starting from rest moves with a uniform acceleration of 0.1 ms–2 for 2 minutes.
Find (a) the speed acquired, (b) the distance travelled.
Q 35.
A scalar quantity has ?
(a) magnitude only
(b) direction only
(c) both direction and magnitude
(d) none of these
Q 36.
Starting from a stationary position, Rahul paddles his bicycle to attain a velocity of 6 m/s in 30 s.Then he applies brakes such that the velocity of bicycle comes down to 4 m/s in the next 5 s.Calculate the acceleration of the bicycle in both the cases.
Q 37.
What does the slope of a speed-time graph indicate ?
Q 38.
State velocity-time relation in uniformly accelerated motion. Use graphical method to obtain this relation.
Q 39.
A hydraulic automobile lift is designed to lift cars with a maximum mass of 3000 kg.The area of the piston carrying the load is
.What maximum pressure would the smaller piston have to bear ?
Q 40.
A solid body of mass
kg and volume
is put in water.Will the body float or sink ?
Q 41.
What force acting on an area of
will produce a pressure of 500 Pa ?
Q 42.
What is meant by scalars and vectors?
Q 43.
Distinguish between speed and velocity.
Q 44.
A train travels some distance with a speed of 30 km/h and returns with a speed of 45 km/h.Calculate the average speed of the train.
Q 45.
What remains constant in uniform circular motion ?
Q 46.
A body starts from rest.What is zero ?
Q 47.
Convert a speed of 15 m/s into km/h
Q 48.
Using graphical method,derive the equations
v=u+at and s=ut+
where symbols have their usual meanings.
Q 49.
An iron cylinder of radius 14 cm and length 8 cm is found to weigh 369.6 g.Calculate the density of iron.
Q 50.
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.
