Question:
When will you say a body is in (») uniform acceleration ? (ii) non-uniform acceleration ?
Answer:
(i) A body is said to be in uniform acceleration, when velocity of the body changes by equal amounts in equal mtervals of time. For example, motion of a body falling freely under gravity.
(ii) A body is said to be in non-uniform acceleration,when velocity of the body changes by unequal amounts in equal intervals of time. For example, motion of a car on a highway through city limits.
Motion
Q 1.
Derive graphically the equation of motion for position-velocity relation of a body moving with uniform acceleration.
Q 2.
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 3.
A particle moves over three quarters of a circle of radius r.What is the magnitude of its displacement ?
Q 4.
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 5.
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 6.
What is represented by the graphs in Fig.?
.
Q 7.
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 8.
Why is a slight blow on a cork of bottle fully filled with a liquid sufficient to break the bottle ?
Q 9.
Write the three equations of uniformly accelerated motion. Give the meaning of each symbol in them.
Q 10.
When will you say a body is in (i) uniform acceleration? (ii) nonuniform acceleration?
Q 11.
Name the quantity that represents rate of change of velocity ?
Q 12.
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 13.
A body starts from rest.What is zero ?
Q 14.
What will be the initial velocity of an object under free fall?
Q 15.
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 16.
Why does a person feel pain when he stands on a pile of gravel than when he stands on a bed of sand ?
Q 17.
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 18.
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 19.
Under what conditions(s) is the magnitude of average
Q 20.
What conclusion do you draw when displacement-time graph of a body is as shown in Fig.?
Q 21.
What is the relationship between the buoyant force on an object and the liquid displaced by it ?
Q 22.
The speed-time graph for a car is shown is Fig.
(a) Find how far does the car travel in the first 4 seconds.Shade the area on the graph that represents the distance travelled by the car during this period.
(b) Which part of the graph represents uniform motion of the car ?
.
Q 23.
What is pressure in case of fluids ? What is Pascal’s law ?
Q 24.
A body thrown vertically upwards reaches a maximum height h.It then returns to ground.Calculate the distance travelled and the displacement.
Q 25.
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 26.
What can you say about the motion of an object whose distance-time graph is a straight line parallel to the time axis ?
Q 27.
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 28.
Explain the terms : uniform motion and non-uniform motion with examples.
Q 29.
Draw speed-time graph for a body (i) at rest (ii) in uniform motion (iii) in uniformly accelerated motion.Discuss the results briefly.
Q 30.
A force of 16 N is distributed uniformly on one surface of a cube of edge 8 cm.Find the pressure on this surface.
Q 31.
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 32.
Relative density of silver is 10.8.The density of water is
.What is the density of silver in SI units ?
Q 33.
The density of turpentine oil is
.What will be its relative density ?
Q 34.
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 35.
Pascal’s law states that a fluid in a confined space expands into every possible space if it is put under pressure.This law plays a very important role in our lives.Give three applications with brief description.
Q 36.
An electric train is moving with a velocity of 120 km/h. How much distance will it move in 30 s ?
Q 37.
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 38.
When will you say a body is in (») uniform acceleration ? (ii) non-uniform acceleration ?
Q 39.
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 40.
Why is it easier to swim in sea water than in river water ?
Q 41.
Why are sleepers used below the rails ?
Q 42.
Under what condition(s) is the magnitude of average velocity of an object equal to its average speed?
Q 43.
A trolley, while going down an inclined plane, has an acceleration of
starting from rest.What will be its velocity 3 s after the start ?
Q 44.
What is SI unit of speed ? Is it same for velocity ?
Q 45.
What is the acceleration of a body moving with uniform velocity ?
Q 46.
If velocity-time graph of a body is as shown in Fig.,what is the nature of motion ?
Q 47.
What can you calculate from speed-time graph of a body ?
Q 48.
Use graphical method to derive the relation
-
= 2 as,where the symbols have their usual meanings.
Q 49.
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 50.
What is Archimedes’ Principle ? How can it be experimentally verified ?
