HCI Worksheet 1 Basic Ideas in Physics (answers)

Hwa Chong Institution Sec 3 (Physics) 1 Name: __________________________________________ Class: _________ Date: ____________ Sec 3 Physics Worksheet 1: Basic Ideas in Physics Multiple Choice Questions 1. A stopwatch hand stops in the position as shown. What is the reading? A 21.2 s B 22.4 s C 27.6 s D 32.0 s E 38.0 s N92/I/1 2 It takes 13.8 s for a pendulum to swing from X to Y and back again twenty times. What is the period of the pendulum? A 0.345 s B 0.690 s C 1.38 s D 4.60 s E 13.8 s

Hwa Chong Institution Sec 3 (Physics) 2 3 A student used a vernier caliper to measure the diameter of a wooden cylinder. The diagram shows an enlargement of the calipers scale. What was the reading recorded? A 2.40 cm B 1.64 cm C 0.62 cm D 0.42 cm 4 A student has been asked to calculate the volume of a piece of wire, which is about 80 cm long and about 0.2 cm in diameter. Which of the following instruments should the student use? Length Diameter A Metre rule Micrometer B Metre rule Vernier calipers C Micrometer Vernier calipers D Vernier calipers Micrometer N97/I/1 5 Which of the following physical quantity is measured using a micrometer? A current B length C time D weight N98/I/1 6 The diagram shows part of a micrometer screw gauge. What is the reading shown? A 5.31 mm B 5.79 mm C 5.81 mm D 6.31 mm N91/I/2

Hwa Chong Institution Sec 3 (Physics) 3 7 The diagram shows part of the vernier scale on a pair of calipers. Which reading is correct? A 2.74 cm B 3.10 cm C 3.26 cm D 3.64 cm N99/I/1 8 The diagram shows a micrometer screw gauge. What is the reading shown? A 5.25 mm C 7.02 mm B 5.48 mm D 7.48 mm N2000/I/1 9 The diagram shows a micrometer scale. Which reading is shown? A 5.64 mm C 7.16 mm B 7.14 mm D 7.64 mm N2002/I/1

Hwa Chong Institution Sec 3 (Physics) 4 10 One oscillation of a swinging pendulum occurs when the bob moves from X to Y and back to X again. Using a stopwatch, which would be the most accurate way to measure the time for one oscillation of the pendulum? A Time 20 oscillations and multiply by 20. B Time 20 oscillations and divide by 20. C Time one oscillation. D Time the motion from X to Y and double it. N2003/I/1 11 The diagram shows part of a vernier scale. What reading is correct? A 30.5 mm B 33.5 mm C 38.0 mm D 42.5 mm N2004/I/1

Hwa Chong Institution Sec 3 (Physics) 5 Discussion Questions Derived Quantity Formula S.I. unit Another common unit Area of a rectangle hlength widt 2m 2cm Density mass volume 3kg m− 3g cm− Average speed total distance total time 1m s− 1km h− 1 Fill up the table with the appropriate formulas and units: 2 Fill in the blanks with units of the appropriate prefixes. (a) 1 kg = 103 g (c) 1 mA = 31 10 A− (b) 1 s = 10-6 s (d) 1 GW = 109 W 3 When using the Vernier callipers, (a) state two precautions you would take in order to make your determ ination of the diameter of a coin as accurate as possible. Check zero reading and incorporate it into the measurement if necessary; Obtain several readings of its diameter (by rotating the coin) and calculate the average value; (b) state two ad vantages of using this instrument compared with using a rule reading in millimetres for making this measurement. Jaws can close around the round object properly, making the measurement of the diameter easier; More precise measurement as precision is up to .0 01 cm. Ruler can only measure up to .01 cm. 4 When using the micrometer screw gauge, state the purpose of the ratchet. Ratchet prevents the user from exerting too much pressure on the object to be measured.

Hwa Chong Institution Sec 3 (Physics) 6 5 A pile of 500 sheets of paper has a mass of 2.0 kg. The pile is 300 mm long, 200 mm wide, and 50 mm thick. Calculate (a) the thickness of one sheet; 3 450 10Thickness 1 10 m (1 s.f.)500 − −= =  (b) the mass of one sheet; . 320Mass of 1 sheet 4 10 kg500 −= =  (c) the volume of the pile; 9 3 3Volume of the pile 300 200 50 10 3 10 m−−=    =  (d) the density of the paper; 23 3 2Density 7 10 kg m3 10 − −= =  (e) the mass of a one-square-metre sheet of this paper. ( )( )( ) 2 3 2 4 2mass 7 10 kg m 1 m 1 10 m 7 10 kg− − −=   =  [Avison] 6 When a block of metal is hung in air from a spring balance, the reading is 9.6 N. (a) What is the weight of the block of metal? .9 6 NWeight= (b) Assuming that the weight of a 1 .0 kg mass is 10 N, calculate the mass of the block of metal? .0 96 kg

Hwa Chong Institution Sec 3 (Physics) 7 (c) The figure shows a displacement can which has been filled with water. When the block of metal in (a) is lowered into the can until it is totally immersed in the water, 110 cm 3 of water overflows. Calculate the density of the metal. . 33 3 960 g 8 7 g cm or 8700 kg m110 cm −−==Density 7 The following figure shows a simple pendulum suspended from a clamp. (a) Describe briefly how you would use a stopwatch or a stopclock to determine, as reliably as possible, the period of oscillation of a pendulum. (b) A student obtains the following values for the time for 20 complete oscillations of a pendulum. 14.6 s 14.7 s 14.5 s 14.6 s 14.7 s Determine the period of the pendulum. ..... .14 6 14 7 14 5 14 6 14 7Period 0 731 s 20 5 ++++==  20 and 5 in the denominator are exact numbers. N97/II/1 Pendulum bob

Hwa Chong Institution Sec 3 (Physics) 8 Further Questions (i) In a simple pendulum , what is the physical quantity that determines the period T of the oscillation? What is the relationship between T and that quantity? Length of the pendulum. or 2 = LT L T g (ii) One important consideration when doing a pendulum experiment is to ensure that the maximum angle of swing must not exceed 10o. What is the reason for it? The relationship in (i) is only valid for small angles. (iii) Imagine you are explaining what it meant by an oscillation of the pendulum to a Sec 1 student, how would you describe it? (iv) Why do we need to repeat the timing several times? Correct the human reaction time [??]. The human reaction time is slightly greater than 0.1s. (v) What is the most significant source of error in this experiment? The experimenter. Human reaction time. (vi) The typical stopwatch used in the laboratory can measure up to centi or milliseconds. Should we take the readings to that level of precision? No. The readings cannot be more precise than the error. (vii) After a few swings, the amplitude of the oscillations becomes smaller as air resistance is dissipating energy from the pendulum. Will the period of the pendulum change in response? No. The period of oscillation remains constant. It is dependent on the length of the pendulum only. (viii) If the pendulum bob is changed to a more massive one, would the period T of the oscillation change? As with the answer in part (vii), the period T will not change.

Hwa Chong Institution Sec 3 (Physics) 9 8 In the opening scenes of the movie Raiders of the Lost Ark , Indiana Jones trie d to remove a gold idol from a booby -trapped pedestal. He replaced the idol with a bag of sand of approximately the same volume (see picture on left). (a) Calculate the ratio of the mass of the idol to the mass of the b