Question:
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?
Answer:
: Total displacement in this case ("round trip") = 0m
Let us assume time taken = T secs.
Average velocity (v) = Total Displacement ÷ Time Taken = 0 ÷ T = 0 m/sec
Note: In the above question, there are two important words "round trip" and "average velocity".
While solving numericals, focus on such words. These two words help in understand we need to compute displacement not distance. If average speed is being asked, we need to compute distance traveled.
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.
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 12.
What does the slope of distance-time graph indicate?
Q 13.
Distinguish between speed and velocity.
Q 14.
What is the acceleration of a body moving with uniform velocity ?
Q 15.
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 16.
(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 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.
When will you say a body is in (i) uniform acceleration? (ii) nonuniform acceleration?
Q 20.
A scalar quantity has ?
(a) magnitude only
(b) direction only
(c) both direction and magnitude
(d) none of these
Q 21.
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 22.
Explain what is meant by uniform circular motion.Give at least three examples.
Q 23.
What force acting on an area of
will produce a pressure of 500 Pa ?
Q 24.
Why do objects float or sink when placed on the surface of a liquid ?
Q 25.
A particle is moving in a circle of diameter 5 m. Calculate the distance covered and the displacement when it completes 3 revolutions.
Q 26.
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 27.
What does the slope of a speed-time graph indicate ?
Q 28.
A body of 2.0 kg floats in a liquid.What is the buoyant force on the body ?
Q 29.
Why do you feel lighter when you swim ?
Q 30.
What is Archimedes’ Principle ? How can it be experimentally verified ?
Q 31.
Is displacement a scalar quantity ?
Q 32.
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 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 metallic sphere of radius 2.0 cm is completely dipped in water.Find the force of buoyancy on it.
Q 35.
Human corpse always floats on the surface of water,but the head always stays within water.Why ?
Q 36.
What is meant by scalars and vectors?
Q 37.
Fill in the blanks :
If the position of an object does not change with time, it is said to be at _____.
Q 38.
Ahmed is moving in his car with a velocity of 45 km/h.How much distance will he cover (a) in one minute and (b) in one second ?
Q 39.
A body starts to slide over a horizontal surface with an initial velocity of 0-5 m/s. Due to friction, its velocity decreases at the rate of 0.05
.How much time will it take for the body to stop ?
Q 40.
A body starts from rest.What is zero ?
Q 41.
Convert a speed of 15 m/s into km/h
Q 42.
Define the term uniform acceleration.Give one example of uniformly accelerated motion.
Q 43.
State velocity-time relation in uniformly accelerated motion. Use graphical method to obtain this relation.
Q 44.
A solid body of mass
kg and volume
is put in water.Will the body float or sink ?
Q 45.
Calculate the pressure when a force of 200 N acts on an
Q 46.
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 47.
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 48.
A train is travelling at a speed of 90 kmh–1. Brakes are applied so as to produce a uniform acceleration of – 0.5 ms–2. Find how far the train will go before it is brought to rest.
Q 49.
A trolley, while going down an inclined plane, has an acceleration of 2 cm s
–2. What will be its velocity 3 s after the start?
Q 50.
An object travels 16 m in 4 s and then another 16 m in 2 s. What is the average speed of the object ?
