North Vista 5105 Prelim 4NA 2024 MS

1 Secondary 4NA Preliminary Examination Paper 2024 Marking Scheme Paper 1 1 C Weight is a force and forces have direction in addition to magnitude. 2 C The radius of the Earth is 6 378 000m 3 C distance travelled = area under graph = ½ x base x height = ½ x 3 x 9 = 13.5m 4 B Gravitational acceleration is constant. Since there is acceleration, the velocity must be increasing. 5 B The object does not move to the left or right → forces to the left and to the right must be equal and opposite to each other. Object accelerates downwards → force acting down must be greater than force acting up. 6 A Mass is measured with a beam balance or an electronic balance 7 D Least density → lowest amount of mass packed into the same volume Thus, to have the same mass, an object with a lower density must be bigger than another object with a larger density 8 A Formula for pressure 9 A Molecules in both gas and liquid are able to move freely but the force of attraction between molecules in a gas is weaker than that between molecules in a liquid 10 A Gas has no fixed volume and shape 11 B With the saucer, the air above the coffee cannot circulate 12 A Definition of wavefront 13 C Amplitude is the largest displacement from rest position 14 B Gamma radiation kills cells 15 A Q = It = 4 x 30 = 120C 16 B Ammeter connected in series while voltmeter connect in parallel to the lamp 17 C Current flowing out of battery = current flowing into battery 18 B Think reverse alphabetical order clockwise (Green and Yellow, Brown, Blue) 19 D Fuse and switch ha ve to be placed along the live wire (between live terminal and the appliance) 20 D gamma radiation is an EM Wave, beta is an electron and alpha is a helium nucleus, thus gamma is the most penetrative

2 Paper 2 Section A Qn Solution Marks 1 a 3.0 x 108m/s [1] b v = fλ 3.0 x 108 = f x 920 x 10–9 f = 3.26 x 1014Hz or 3.3 x 1014Hz [1] [1] c radiowave transmission of radio signals , transmission of television signals , RFID tags, radio telescope for radio astronomy OR microwaves transmission of mobile phone signals, satellite communication, heating of food in microwave ovens, radar [1] [1] 2 a a = (v – u)/t = (28 – 0)/3.5 = 8.0m/s2 [1] [1] b F = ma = 620 x 8 = 4960N [1] 3 a [1] time/min 100 10 20 30 40 50 60 80 0 20 40 60 distance /km

3 b Working with points chosen clearly shown on graph. Gradient correctly calculated to 3 significant figures. [1] [1] 4 statement true/false [3] The SI unit for density is g/cm3. false All electromagnetic waves are transverse waves. true When water freezes into ice, the temperature remains unchanged because the internal potential energy remains unchanged. false Metals are good conductors of heat because they have free electrons. true Radiation does not occur in a vacuum. false An electric appliance with double insulation does not require an Earth wire. true 1m for every 2 correct answer 5 a I agree. A white surface is a poorer emitter of heat. This reduces the heat loss through radiation. [1] [1] b The water molecules slide over each other (move) slower. [1] c Plastic is a poor conductor of heat . This prevents the user from being burnt while carrying the kettle. [1] 6 a 14 represents the total number of protons and neutrons. OR 14 is the nucleon number. [1] bi electron [1] bii 100g → 50g, 1 half-life 50g → 25g, 2nd half-life 2 half-lives = 11 460 years 1 half life = 11460/2 = 5730 years [1] [1]

4 Section B 7 ai Power is the rate of doing work. OR Power is the rate of energy transferred. [1] bi Work done = F x d 105 = F x 0.70 F = 150N [1] [1] bii 105J [1] biii Ek = ½ mv2 105 = ½ x 0.20 x v2 v = 32.4m/s [1] [1] biv Ep = mgh 105 = 0.20 x 10 x h h = 52.5m [1] [1] 8 ai 8Ω resistor has the greatest potential difference. [1] aii Since V = IR, and the current flowing through all three resistors is the same, therefore 8Ω resistor has the greatest potential difference. [1] [1] b OR OR [1] ci cost = electrical energy in kWh x price of 1 kWh of electricity = 2.0 x 2.5 x 0.25 = $1.25 [1] cii P = VI 2000 = 240 I I = 8.33A or 8.3A [1] [1]

5 ciii 10A fuse The fuse chosen must have a rating slightly higher than the expected (working) current. [1] End of Paper