2015 Physics Exam : Short Answer Questions

Short Answer Questions for 2015 Physics Exam paper. The Answers are provided at the end of the post.  Attempt to answer the questions first by commenting below. Then compare your answers with ours.

QUESTION 31
A ball is projected into the air with an initial velocity of 20m/s at angle of 60° above the horizontal. The ball lands at a distance of X meters from the launching point.
a). What is the horizontal component of the velocity of the ball?          (2 marks)
b). How long was the ball in the air?                                                 (3 marks)
c). What is the horizontal distance X travelled?                                   (2 marks)​

​During a snooker competition, a 200 grams ball A moving with velocity V! as show in the diagram above, collides head-on with an identical ball B that was at rest. After the collision, ball A remains at rest while ball B moves on with a velocity of 4m/s.
a). With what speed was ball A moving before the collision?                                             (1 marks)
b). What is the momentum of the ball B after the collision?                                              (2 marks)
c). What is the momentum of ball A after the collision?                                                    (1mark)
d). What are the directions of the forces exerted by balls on each other?                           (2marks)
e). Which of the three laws of motion (Newton’s Laws) is being applied in part a). above?   (1 mark) 

QUESTION 33
A boy can carry a 2kg box and walk one meter to the right. Then he raises it by 1m and places it on a shelf.
a). Explain why the boy cannot do any work in carrying the box horizontally.                     (2 marks)
b). Calculate the work the boy does in raising the box vertically and placing it on the shelf. (2 marks)
c). If the boy takes one minute to raise the box vertically, what is the power used in raising the box?
                                                                                                                                 (2 marks)
d). What form of energy does the box have as a result of being raised and placed on the shelf? (1mark) 

QUESTION 37
a) How many changes in phase are involved in working out the total amount of heat required to raise the temperature of ice at -15°C to steam at 115°C? (1 mark)

b) In a hot climate, the inhabitants often wear while coloured clothes. Explain why they do that? (1 mark)

c) An electric boiler with power rating of 125 kW is used to complete evaporate water at a temperature of 100°C in 2 minutes. If the initial temperature of water is 20°C, how much in kilograms is the mass of the water? (3 marks)

d) Explain the difference between heat and temperature. (1 mark)

e) You bought two cooking pots with same masses and volumes. One is made of copper which has a specific heat capacity of 400J/kg°C and the other is made of aluminum whose specific heat capacity is 900J/kg°C . If the same amount of heat is applied to both cooking pots with equal amount of rice and water in them, in which of the pots will rice cook faster? (1 mark) 

QUESTION 38
a) The speed of a wave propagating is 330 m/s in air at 0°C. If the frequency is 440 Hz, what is its wavelength? (1 mark)

b) A ship sends out a sound wave and receives an echo after 1 second. If the velocity of the sound in water is 1500 m/s, determine how deep is the water. (1 mark)

c) All AM radio stations are assigned frequencies in the range between 550 and 1600 Hz. The speed of propagation of radio waves is 3 x10!m/s . What wavelengths do these radio waves span? (2 marks)

d) Waves in a deep region of a ripple tank have a velocity of 6 cm/s and wavelength of 4 cm. They pass into a shallow region where their speed is 4cm/s.
i). Calculate the wavelength of the wave in the shallow region. (1 mark)
ii). Calculate the frequency of the waves in the deep region. (1 mark)
iii). Calculate the frequency of the waves in the shallow region (1 mark)

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Note: check for the Multiple choice part on the other posts.  Answers provided on the Answer tab above.