Mechanics I Question Paper

Mechanics I

Course:Bachelor Of Telecommunication And Information Engineering

Institution: Kenyatta University question papers

Exam Year:2009

KENYATTA UNIVERSITY
UNIVERSITY EXAMINATIONS 2009/2010
FIRST SEMESTER EXAMINATION FOR THE DEGREE OF BACHELOR OF
EDUCATION, BACHELOR OF SCIENCE AND BACHELOR OF
TELECOMMUNICATION AND INFORMATION TECHNOLOGY
SPH 100 MECHANICS I

DATE: Wednesday 23rd December, 2009 TIME: 4.30 p.m. – 6.30 p.m.

INSTRUCTIONS
Attempt question 1 and any other TWO questions. Question 1 has 30 marks, others
have 20 marks each.
______________________________________________________________________
Unless stated the following constants should be used. Earth’s radius 6400km, Earth’s
density 5500 Kg/M3 Gravitational constant, G = 6.67 X 10-11 N m2/kg2
______________________________________________________________________
Q1.
a)
What is the meaning of the word Errors as used in experimental
measurements? [2
marks]

b)
i)
What’s a unit of a physical property and when is a unit
fundamental?
[2
marks]

ii)
Derive the form of the equation of a pendulum’s periodic time
assuming that the period of the pendulum depends on pendulum’s
length, mass of the bob, and earth’s gravitational field.

[4 marks]
c)
i)
What
is
a
projectile?
[2
marks]

ii)
List all variables required to describe the motion of projectiles.

[2 marks]
Page 1 of 5
iii)
Use the variables in (i) derive the equation(s) describing the
motion a projectile motion.

[2 marks]
Consider a stone thrown with velocity of 15 m/s at an angle of 60o to the
vertical.
Hence calculate the following:
iv)
The time it takes before the stone hits the ground. [2 marks]
v)
The range of the stone.

[2 marks]
vi)
The velocity before impact.

[2 marks]
vii)
The maximum height attained by the stone during this time.
[2 marks]
d)
i)
What
is
centripetal
force?
[2
marks]
Consider a satellite rotating around the earth. If the earth has the
following parameters,
ii)
Write down the equation for the planets period in terms of its
distance from the earth.
iii)
Write down the expression for the satellite’s period round the
earth.

[2 marks]
iv)
Hence determine the distance at which the satellite is iso-
synchronous with the earth’s revolution. Note that the satellite
rotates round the earth in 24 hours.

[2 marks]

Q2.
Derive the equations of motions for objects undergoing displacement at constant
velocity
and
constant
acceleration.
[4
marks]
i)
An object starts with an initial velocity V0. It suddenly accelerates at a
constant rate, a, over a distance S to final velocity, V. Derive an
expression that expresses the displacement S in terms of initial and final
velocities V0 and V.

[6 marks]
ii)
Consider a car moving at a speed of 40 m/s. The driver suddenly applies
the brakes and the car achieves a constant deceleration of 5 m/s. Calculate
the distance covered before car finally comes to rest.
[6 marks]
iii) How
much
time
t, it takes before the car comes to rest?
[4 marks]
Page 2 of 5
Q3.
a)
i)
State Newton’s first and second laws of motion.
[3 marks]
ii)
Under what circumstance does Newton’s second law of motion
lead to conservation of momentum where momentum is the
product of mass and velocity?

[4 marks]
b)
A car weighing 800 kg is moving north at a speed of 25 m/s collides with
another car weighing 600 kg and moving at a speed of 10 m/s in the same
direction.

i)
Identify the Newton’s law that applies to this situation.

[3 marks]
ii)
If the cars stick together after the collision calculate the final
velocity of the two cars.

[5 marks]
iii)
Redo (ii), if second car was moving south at the same speed and
the two cars stuck after the collision. In which direction would
they
move?
[5
marks]
Q4.
a)
Identify the different types of friction.

[4 marks]
b)
The figure below shows an arrangement of two blocks, A is 6kg and
hanging on a string an B is 15 Kg on the table. Block B is held to the table
by hook.

Page 3 of 5
The
table’s
coefficients of friction are unknown.
i)
Write down the equation for tension in the string if you assume the table
is
frictionless.
[4
marks]
At t = 0 the Block B is released from hook and Block B slides 4 meters on
the table surface in 2 seconds

ii)
Determine the blocks rate of acceleration.

[2 marks]

iii)
Calculate the tension in the string connecting the two blocks.

[4 marks]

iv)
Determine the table’s coefficient of friction.

[5 marks]

v)
Using this value of coefficient of friction repeat part i., i.e. determine the
tension in the string when the block is held in place by the hook.

[5 marks]
Q5.
Consider the weight suspended as shown in figure below

Page 4 of 5
i)
Write down equations relating the tensions T1 and T2 in the strings to the
other parameters in the figure. [5
marks]
ii)
Determine the tensions in the strings for the positions indicated.

[5 marks]
iii)
What would be the new values of tensions in strings if T2 is moved to
position
2?
[6
marks]
iv)
What would be new values of T1 and T2 if string 1 is moves to position B?

[6 marks]
v)
Which way would the tensions be altered if T1 were to be moved to a
position perpendicular to the vertical wall?

[4 marks]

……………………..

Page 5 of 5

📘 Access 10,000+ CBC Exams With Marking Schemes

Mechanics I Question Paper

More Question Papers

Exams With Marking Schemes

End Term 3 Exams

Mid Term Exams

End Term 1 Exams

Opener Exams

Full Set Exams