# s1y0708 PHYF 114

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```					                              COLLEGE OF ENGINEERING

SEMESTER I 2007/2008

PROGRAMME                      : FOUNDATION

SUBJECT NAME                   : PHYSICS I

SUBJECT CODE                   : PHYF 114 & PHYB 114

DATE OF EXAMINATION : 3RD NOVEMBER 07

TIME                           : 3.30PM – 5.30PM (2 HOURS)

VENUE                          : MPH

1. Jawab semua soalan di bahagian A dan mana-mana 4 soalan di bahagian B.

2. Jawab semua soalan dengan menggunakan pen.

JANGAN BUKA KERTAS SOALAN INI SEHINGGA ANDA DIARAH BERBUAT
DEMIKIAN

Instructions to candidates:

1. Answer all questions in PART A and any 4 questions in PART B.

2. Answer all questions using pen.

DO NOT OPEN THIS QUESTION PAPER UNTIL YOU ARE INSTRUCTED TO DO SO

KERTAS SOALAN INI MENGANDUNGI 6 MUKA SURAT BERCETAK
TERMASUK MUKA SURAT INI.

THIS QUESTION PAPER CONSISTS OF 6 PRINTED PAGES INCLUDING THIS
PAGE.

1
PART A : (Answer all questions - each question worth 2 marks)
(Use g = 9.8 ms-2, G  6.673  10 11 N m 2 kg -2 )

1. A stone is given an initial velocity of 40.0 ms-1 at an angle of 600. What are its
horizontal and vertical displacements after 2.0 s?

2. Figure 1 shows a 50.0N box that is pushed with a horizontal force, 60N at a constat
speed with an inclined angle 30º from the platform. Determine the magnitude of the
friction force.

box
60.0 N

30°
plateform

Figure 1

3. The moon takes 27.32 days to orbit the Earth. Given The radius of the Moon’s orbit is
3.844 X 108 m. Find the centripetal acceleration of the moon.

4. An object is in uniform circular motion as shown in Figure 2 above. Using Work-
Kinetic Energy Theorem find the work done of this object.

v
v
B

A

Figure 2

2
5. An object is launched at an angle θ from the ground of point O as shown in Figure 3.
The velocity at point O is given as vo and the maximum height, h of the object at point
B is 20.0 m. By using conservation of energy, find the vertical component of vo at
point O.

B
vo
h
θ
O

Figure 3

6. Ahmad (mass = 65.0 kg) was at rest. Then he saw a stationary cart (mass = 20.0 kg)
that was 10.0 m in front of him. Finally he decided to run to the cart with a constant
acceleration of 2.0 ms-2.
a) Find Ahmad’s final speed just before he jumped onto the cart.
b) Find Ahmad’s final speed just after he jumped onto the cart.

7. Find the resultant torque if the rod is fixed at point O as shown in Figure 4. (The
weight of the rod is negligible) It is given that F1 is, F2 and F3 are 20.0 N, 30.0 N and
100.0 N respectively.

F1
4m                            6m
O

F2
F3                          Figure 4

8. A particle of mass 3 kg is moving in the xy plane with a constant speed of 4 m/s along
the direction of r = 3i+4j. What is the angular momentum relative to the origin?

3
9. A 8.0-m board of negligible weight is supported at a point 2.0 m from the right end,
where a 5.0-kg object is attached. What mass must be placed at the left end in order to
produce an equilibrium system.

10. A sphere of mass 60.0 kg is located at x = 0.5 m and y = 1.0 m. What is the
magnitude of the gravitational force on a 20.0-kg sphere that is located at the origin
relative to the 60.0-kg sphere?

PART B : (Answer only 4 questions - each question worth 10 marks)

1. a) What is the law of conservation of momentum applies to a collision between two
bodies?                                                                              [1]
b) A 1.5-kg playground ball is moving with a velocity of 3.0 ms-1 directed 30 below
the horizontal just before it strikes a horizontal surface. After touching on the
horizontal surface for 0.5 s, the ball leaves with a velocity of 2.0 ms-1 directed 60
above the horizontal surface.
i) Find the magnitude of the heat lost (K.E) of the system.                           [5]
ii) Find the magnitude of the impulse of the ball.                                     [3]
iii) Find the magnitude of the average resultant force of the ball.                    [1]

2. a) An arrow accelerates from zero to 45.0 ms-1 in 8.0 seconds. How far does it travel if
the acceleration is constant?                                                        [4]
b) i) Briefly described the equation for torque.                                        [2]
ii) A single belt is wrapped around two pulleys as shown in Figure 6. The drive
pulley and the output pulley has a diameter of 40.0 cm and 50.0 cm respectively. If
the top belt tension is essentially 80 N at the edge of each pulley, what are the input
and output torques?                                                                  [4]

4
Figure 6

3. A 200 N boom of length 2 m is pivoted at a point of a wall as shown in Figure 7 below.
A 55 kg load is attached at the right end of the boom. A cable is attached to the right
end of the boom and its left end is attached to the wall. A little boy with mass of 40 kg
is climbing the boom and stay at its centre of gravity. At equilibrium, find
a) the tension in the cable                                                          [5]
b) the magnitude and direction of the force exerted by the wall on the boom          [5]

cable

55kg
boom

Figure 7

4. (a) Define the meaning of density and pressure?                                      [2]
(b) A cubic box 20.0 cm on a side is completely immersed in a fluid as shown in
Figure 8 below. The pressure at the top and the bottom of the box are 105.0 kPa
and 107.8 kPa accordingly. Find the density of the fluid?                         [4]

5
Figure 8

(c ) State Pascal’s law.                                                                  [1]
(d) To inspect a 14,500 N car, it is raised with a hydraulic lift. If the radius of the small
and the large piston are 5.0 m and the 18 m respectively, find the force that must be
exerted on the small piston to lift the car?                                         [3]

5. (a) Figure 9 shows a block weighing 14.0 N, which can slide without friction on an
incline at an angle  = 40.0o, is connected to the top of the incline by a massless
spring of unstretched length 0.450 m and spring constant, k = 120 Nm-1.
(i) Draw the free-body diagram of the block.                                        [1]
(ii) How far from the top of the incline is the block’s equilibrium point?          [2]
(iii) If the block is pulled slightly down the incline and released, what is the period
of the resulting oscillations?                                                  [2]

k

14 N
0.450 m
Figure 9

40o

6
(b) A block whose mass m 680.0 g is fastened to a spring whose spring constant k
is 65.0 Nm-1. The block is pulled a distance of xm = 11.0 cm from its equilibrium
position at x = 0 on a horizontal frictionless surface and released from rest at t = 0.
(i) What is the mechanical energy E of the linear oscillator.                        [2]
(ii) What are the potential energy, U and kinetic energy, K of the oscillator when
the block is at x  1 x m ?
2
[3]

7

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