# Summer Holiday Homework

Mechanics

Nov 14, 2013 (4 years and 8 months ago)

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THS,VK, Cl.XI Physics, Summer HHW, Topic: Unit1 & 2 Session:2013
-
14

Page
1

D
-
II, VasantKunj, New Delhi
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110070

Summer
Holiday Homework

Session 201
3
-
201
4

Name:

_____________________

S.No. :
1

Date: _______/ _
05
_____/ _
2013_
Class: XI
-
A

Subject:

Physics

Topic: Unit1 & Unit 2

GENERAL INSTRUCTIONS:

A: The numerical are based on application of theory content. Attempt them in your physics
notebook as practice assignment.

B
: Do all questions in
sequence.

Unit
-
I: Physical World and Measurement

1.

Check the correctness of the following equations (i) v
2
=u
2
+2aS (ii) K E=1/2 mv
2

2.

Centripetal force acting on a body moving along a circu
lar path depends on (i) mass

of
body (m), velocity of the body (v), radius of circular path (r). Using the method

of dimensions derive the expression for centripetal force.

3.

Rate of flow of liquid through a pipe depends on (i) pressure gradient exist between

the ends of pipe (P/l))(ii)radius of the pipe (r)(iii)co
-
efficient of viscosity of

liquid(η). using the
method of dimensions derive the expression for Rate of flow of

liquid through a pipe.

4.

Energy of a body executing SHM depends on (i) mass of the body(m) (ii) amplitude

with which the body oscillate(a) (iii)frequency of oscillation(ν) using the method

of

dimensions derive the expression for centripetal force.

5.

Convert one Newton into dyne using the method of dimensions.

6.

Assuming that the mass M of the largest stone that can be moved by a flowing river

depends upon ‘v’ the velocity, ‘ρ’ the de
nsity of water and on ‘g’ the acceleration due

to gravity. Using dimensions show that M varies with the sixth power of the

velocity of flow.

7.

State the no. of significant figures of the following

(a) 5.327

10
4

(b) 12.00

(c) 5.07 (d) 9320

(d
) 214.213

8.

The radius of a cylinder is 1.250cm and its length is 5.7324cm.Calculate its area and

volume to the correct significant figures?

9
.

What is the difference between angstrom unit and A.U.?

10
.

What are micron and Fermi?

1
1
.

If x = a + bt + ct
2
, where x is in metres, t in seconds, what is the unit of c?

12
.

The moon is observed from two
diametrically opposite points A and B on earth. The

angle subtended

at the moon by the two directions of observations is 1
0

54’.
Given

the diameter of the earth

to be about 1.276 x 10
7
m. Compute the distance of the

moon from the earth.

13
.

Write the dimensional formulae of the following:

Power, pressure, mass density, momentum
, resistance, acceleration
.

THS,VK, Cl.XI Physics, Summer HHW, Topic: Unit1 & 2 Session:2013
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14

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2

14
.

Find the dimensions of a

and b
in the
equation F= at + bt
2
, where F is force and t is

time.

15
.

Specific resistance ρ of a thin circular wire of radius r cm, resistance R ohms and

length

L is given by Ρ = π r
2
R/L. If r = 0.26+0.01 cm, R = 30 + 2 ohm and L = 75.00

+
0.01cm, find the percentage error in ρ.

1
6
.

If 500g be the unit of mass, 50s the unit of time and acceleration due to gravity

980cms
-
2

be the unit of acceleration, find what will be the new unit of energy?

Unit
-
II: Kinematics

1.

Can a body have zero velocity and finite acceleration? Give one example?

2
.

A car starting from rest acquires a speed of 25ms
-
1

in 10 seconds, after which it

maintains this speed for 10 seconds. Find (a) the acceleration (b) distance traveled

during acceleration (c) total distance traveled?

3
.

Show that the area under velocity
-
time graph gives the displacement of the body?

4
.

A particle moves along x
-
axis in

such a way that its coordinate (x) varies with time
t,

according to expression x=2
-
5t+6t.Find the initial velocity of the particle and

acceleration x in meter and t in second.

5
.

A particle is projected at 60º to the horizontal with a kinetic energy K. What is the

kinetic energy at the highest point?

6
.

Which of the following statements is false for a particle moving in a circle with a

constant angular speed?

(a) the velocity
vector is tangent to the circle

(b) the acceleration vector is tangent to the circle

(c) the acceleration vector points to the centre of the circle

(d) the velocity and acceleration vectors are perpendicular to each other

7
.

The distance traveled by a
n object along the axes are given by x=2t², y = t²

4, z

= 3 t

5. What is the initial velocity of the particle?

8
.

A boy playing o the roof of 10m high building throws a ball with a speed of 10 m/s

at an angle of 30º the horizontal. How far from th
e throwing point will the ball be

at the

height of 10m from the ground?

9
.

If a body travels half of its path in the last second of its fall from rest; find the

time and height of its fall?

10
.

A bullet strikes a uniform plank with a speed of 400ms
-
1

and comes out with the

half the velocity. What would be the velocity if the plank were only half thick?

11
.

A train passes three points A,B ,C at 24 kmh
-
1
,36 kmh
-
1
,54 kmh
-
1

respectively with

uniform acceleration. If the distance AB=2 km, find the
distance BC?

12
.

A stone thrown vertically up went up 98m and came down. How long it was in air?

13
.

A man walks on a straight road from his home to market, which is 2.5km away from

his home with a speed of 5kmh
-
1
. Finding market closed, he returns and
walks back
THS,VK, Cl.XI Physics, Summer HHW, Topic: Unit1 & 2 Session:2013
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14

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3

to home with a speed of 7.5kmh
-
1
. 31. Find out the average speed the person? From

the velocity
-
time graph of uniform accelerated motion deduce the equations of

motion in(i) Velocity

and time

(ii) distance and time

(iii) distance and velocit
y.

1
4
.

A body moving with uniform acceleration describes 20 m in 2
nd

and 30 m in 4
th

second of its
motion. Describe

the distance moved by it in 6
th

second.

1
5
.

A particle is thrown vertically upwards with the velocity of 19.6 m/s .Find

a. the velocity
and acceleration of the particle at the highest point.

b. how high a particle will rise?

c. time taken for rising to the highest point.

d. time taken for falling from the highest point of projection.

e. its velocity, when it comes back to the point of
projection.

14.

A
rubber ball is dropped from a height of 3m. After striking the ground it rises to

height of 2 m . If it remains in contact with the ground for 0.01s
, find

the average

acceleration

during this time.

15.

A particle is moving along x
-

axis. The position of the particle at any instant is given

by

X =
a + bt
2
. Where, a = 6m and b = 3.5 m/s
2
. T is measured in seconds. Find (i) the

velocity of
the particle

at t = 0s and t = 3s. (ii) the average velocity between t = 3s

and t

=
6s.

16.

The velocity of a particle is given by the equation, v = 2t
2

+ 5 cm/s. Find (i) the

change in velocity of

the particle during the time interval between t
1

= 2s and t
2
=

4s (ii) the average acceleration during the same interval and (iii) the inst
antaneous

acceleration at t
2
= 4s.

17.

On a foggy day two drivers spot each other when they are just 80 m apart. They

are travelling at 72 km/h and 60 km/h, respectively. Both of them applied brakes

retarding their cars at the rate of

5 m/s
2
.Determine whether they avert collision

or not.

18
.

A tennis ball is
dropped

on the floor from a height of 4m. It rebounds to a height

of 3m.
If the ball was in contact with the floor for 0.01
s,

what was its average

acceleration

during contact?

19
.

A ball is thrown upwards with an initial velocity of 100 m/s. After how much time

will it

return?
Draw velocity

time graph for the ball and find from the graph (i)

the maximum

height attained by the ball and (ii) height of the ball after 15 s. Take

g = 10 m/s
2
.

2
0
.

A car, starting from rest, accelerates at the rate f through a distance s, then

continues at

constant speed for some time t and then decelerates at the rate f/2

to come to rest. If

the total distance is 5

s
, then

prove that s = ½ ft
2
.

2
1
.

The position coordinate of a moving particle is given by x = 6 + 18t + 9t
2

(x in

metres and

t in seconds). What is its velocity at t = 2 sec?

THS,VK, Cl.XI Physics, Summer HHW, Topic: Unit1 & 2 Session:2013
-
14

Page
4

2
2
.

Derive kinematic equations of motion f
or uniformly accelerated motion
by Calculus

method.

Investigatory Projects
-

Physics (2013
-
14)

As per C.B.S.E. guidelines, all students have to prepare one Investigatory Project carrying
3 marks. All students are therefore, advised to prepare one Investigatory Project on any
one of the following topics or a
ny other topic of their choice based on concept of physics
after consulting the teacher during the summer vacation.

POINTERS FOR MAKING PROJECT REPORT

The material should be placed and bound in the following order:

1. Top Sheet of transparent plastic

Th
e top page of your report should carry the
following information in printed form or handwritten in neat block letters:

Title of Project:

Name of Student:

Roll Number:

Date of submission:

2. Aim of Project

3. Apparatus required

4. Principle/theory

5. construction with labeled diagram,

6. Working

7. Observations

8. calculations,

9. Result/ Conclusions

10. Applications,

11. Graphs if any,

12. References/bibliography

13. Back cover
of
plastic: may be opaque or transparent

THS,VK, Cl.XI Physics, Summer HHW, Topic: Unit1 & 2 Session:2013
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14

Page
5

List of Investigatory Pro
jects

1.

To demonstrate that a centripetal force is necessary for moving a body with a

uniform speed along a circle, and that the magnitude of this force increases with

increase in angular speed.

2.

To demonstrate inter
-
conversion of potential and
kinetic energy.

3.

To demonstrate conservation of linear momentum.

4.

To demonstrate the law of moments.

5.

To demonstrate the effect of angle of launch on range of a projectile.

6.

To demonstrate that the moment of inertia of a rod changes with the change of

position of a pair of equal weights attached to the rod.

7.

To study variation of volume of a gas with its pressure at constant temperature

using a
doctors’ syringe
.

8.

To de
monstrate Bernoulli's theorem with simple illustrations

9.

To demonstrate free oscillations of different vibrating systems.

10.

To demonstrate resonance with a set of coupled pendulums.

11.

To demonstrate longitudinal and transverse waves.

12.

To demon
strate resonance using an open pipe.

Note: Complete the practical file, activity file and the investigatory project and
submit the same within one week after re opening of school i.e.by 7
th

of July.2013.

Name of Teacher: R.K.Sharma