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Unformatted text preview: STUDENT ID NO MULTIMEDIA UNIVERSITY SECOND TRIMESTER SUPPLEMENTARY EXAMINATION,
2008 f 2009 SESSION PPH 0075 —— PHYSICS I
( All sections f Groups ) 4‘h FEBRUARY 2009
9.00 am. — 11.00 am.
(2 Hours) INSTRUCTIONS TO STUDENT 1. This question paper consists of 7 printed pages with 5 questions ONLY. 2. Attempt THREE out of FIVE questions ONLY. All questions carry equal marks
and the distribution of the marks for each question is given. 3. All workings must be shown where applicable. . Write all your answers CLEARLY and ORDERLY in the answer booklet
provided. DJ Physical Constants Electron mass, In, Proton mass, mp
Elementary charge, e
Gravitational constant, G
Gas constant, R Hydrogen ground state, E0
Boltzmann’s constant, kB
Compton wavelength, Kc
Planck’s constant, h Speed of light in vacuum, c
Rydberg constant, RH
Acceleration due to gravity, g luniﬁed atomic mass unit, u
1 eV Avogadro’s number, NA Threshold of intensity of hearing, I,
Coulomb constant, k Perrnlttivity of free space, 86 (or K0)
Permeability of free space, no ll I1 [I ll If If 9.11 x 10'3‘kg 1.67 x 10'27kg 1.602 x10'19 C 6.67 x 10"1 N.m2kg'2
8.314 J/Kmol 13.6 eV 1.38 x1023 J/K
2.426 x 10'12 m
6.626 x 10'3“ 1.5 3.0 x 108 m/s 1.097 x107 m" 9.81 m s'?‘ 931.5 MCV/C2
160x10”1 6.022 x1023 motl
1.0 x10'12 Wm'2
8.988 x 109 N.m2C'2
8.85 x 10'12C2/Nm2 47: x 10'7 Tm/A PPHOOTS PHYSIC 1 FEBRUARY 2009 Answer any THREE questions. Question 1 [15 marks] a) Given the equations below, where x refers to distance travelled, v and u the speed, a
the acceleration, and tthe time. Show whether it is dimensionally correct. i. x = vﬁ + 2a: [3 marks] 13) Figure 1 In Figure 1, ﬁnd the magnitude and direction of the resultant force.
[6 marks] c) At a point, an antelope is running at a maximum Speed of 50 km/h and a cheetah is
trying to catch it and run as fast as 75 km/h. If the antelope is 40 m ahead of the
cheetah, 1. how much time the cheetah need to catch the antelope?
[4 marks]
ii. how far did the antelope run when the cheetah catch it? [2 marks] Continued... SD/AMM l/S PPH0075 PHYSIC 1 FEBRUARY 2009 Question 2 [15 marks! a) The three blocks in Figure 2 are connected by massless strings that pass over
frictionless pulleys. The acceleration of the system is 2.35 m/s2 to the left and the
surfaces are rough. 10.0kg Figure 2
Calculate, i. the tensions in the strings
ii. the coefﬁcient of kinetic friction, pk between blocks and surfaces if M for
both blocks are the same.
[7 marks] b) A 65 kg man is standing on a 6.0 m ladder that leans against a wall at a point 4.8 m
above the ground. The ladder is uniform and has a mass of 15.0 kg as shown
in Figure 3. ~72.;:_ 2v‘6'.1:n. .“_:'5?;;i:2,:<”:_~"’;.. 2.:Vu' . ‘ :r mm. Figure 3
Assuming that the wall is frictionless (but the ground is not), i. draw a free body diagram of the ladder. [2 marks]
ii. determine the normal forces at points A and B. [5 marks]
iii. determine the frictional force at pointA. [1 mark] Continued. . . SDIAMM 2/5 PPHOOTS PHYSIC 1 FEBRUARY 2009 Question 3 {15 marks! :1) Your car of mass 745 kg runs out of gas. You need to push it up a hill to get to a
gas station. The hill rises 3.0 m for every 80.0 m horizontally you travel. You push
with a constant force of 600 N on the car as you move the car 650 m to the gas
station. Find the work done by i. your force on the ear= [2 marks]
ii. the force of gravity acting on the car [3 marks]
iii. the normal force of the road acting on the car [2 marks] b) A 6000 kg freight car rolls along rails with negligible friction. The car is brought to
rest by a combination of two coiled springs as shown in Figure 4. Figure 4 Both Springs obey Hooke‘s law with k; = 1850 N/m and k2 = 4400 N/rn. After the
ﬁrst Spring compresses a distance of 45.0 cm, the second spring (acting with the
ﬁrst) increases the force. If the car is brought to rest 80.0 cm after the ﬁrst contact
with the twospring system, ﬁnd the car‘s initial speed. [4 marks] 0) A 100 g bullet is ﬁred from a riﬂe having a barrel 0.70 m long. Assuming the origin
is placed where the bullet begins to move, the force (in N) exerted on the bullet by
the expanding gas is 17000 + 12000):  28000x2 where x is in meters. Determine the work done by the gas on the bullet as the bullet travels the length of
the barrel.
[4 marks] Continued. .. SD/AMM 3/5 PPHOQTS PHYSIC 1 FEBRUARY 2009
Question 4 (15 marks! a) A satellite of total mass 300 kg goes around the Earth of mass 5 .98 x 1024 kg in a
circular orbit of radius 9.6 x 106 m.
1. Calculate the gravitational force acting on the satellite. [3 marks] ii. An astronaut in the satellite experiences a state of “weightlessness”.
Explain. [2 marks] b) Two objects of masses m and M are separated by a distance re and the separation
changes to rb as shown in Figure 5. Figure 5 Find the change in potential energy (AU) from ra to n, in terms of G, M, ra and rb.
[3 marks] c) A thin wire with a diameter of 2.8 mm and a length of 1.0m is put horizontally to
two supporting wall which are separated by 1.0 m. The middle point of the wire
shifted 2 cm down when a mass of 10 kg is hanged at that point as shown in Figure 6. 10 kg
Figure 6
Calculate the Modulus Young, E for the wire
[7 marks]
Continued... SD/AMM 4/5 PPHOOTS PHYSIC 1 FEBRUARY 2009 Question 5 (15 marks] a) At t = 0 s, a 800 g mass is at rest at one end of a horizontal Spring with k = 200
N/m. The mass is then struck by a hammer which gives it an intial speed of 3.5 m/s.
Detemine for this motion its, i. period, T and frequency, f [3 marks]
ii. amplitude, A [2 marks]
iii. maximum acceleration [2 marks] b) A gas undergoes the following thermodynamic processes: Isobaric expansion,
heated at constant volume, compressed isothermally, and ﬁnally expands
adiabatically back to its initial pressure and volume. Sketch all the processes on the
same pV graph. [4 marks] c) An ideal gas has undergoes two processes AB and BC. 8 k] of heat is supplied to
the process AB and 4 Id of heat is dissipated from the gas. P(x 105 Pa) 3.0 V (m3)
0.02 0.04
Calculate,
i. the work done for AB and BC, [1 mark] ii. the changes in internal energy for AB and BC ,
[3 marks]
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