Grade 12 science

Inzf
timer Asked: May 24th, 2018

Question Description

pls help with these. It’s has to do with motion and newton’s Law’s using surfboards as the subject. Thanks so much in advance

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SBA SVA03 ALTERNATIVE ASSESSMENT TASK IEB MASTER SCIENCE wave." and turned around to paddle away from it with all I have to enable me to get into the Aaron recalled his record 19,2 m wave: "I saw a huge wave approaching on the horizon for 12 seconds until he reached a speed of 4 ms-', when the wave caught up with him. It was determined that he started paddling (away from the wave) from rest, and paddled The combined mass of Aaron and his surfboard is 85 kg. The wave was moving at a constant speed of 45 km-h-' towards Aaron 1.1. What is the net force acting on the wave? Explain your answer. 1.2 What was the speed of the wave, in meters per second? 1.3 How far did the wave travel during the 12 seconds that Aaron was paddling away from it? (2) "Heriotary (1) (3) (5) 1.4 Determine the magnitude of the net force on Aaron and his surfboard during the 12 s period during which he paddled from rest to 4 m.s-'. 1.5 What was the distance between Aaron and the wave when he started paddling (4 away from it? 1.6 Draw a rough position vs time graph for the motion of Aaron as well as for the wave on the same set of axes, from the moment he started paddling until the wave caught up with him. Indicate all relevant points on the axes. (6) mi IEB MASTER SCIENCE The take-off ALTERNATIVE ASSESSMENT TASK SBA SVA03 The most crucial part of catching a wave is the "take-off" where the surfer stands up on the board (after matching the speed of the wave), and then surfs down from the top (crest) of the wave to the bottom (trough). Big oceanic waves move much faster than wave surfers use specifically designed surfboards (called "guns") which help them to smaller waves (due to many reasons beyond the scope of our curriculum), therefore big speed, to gain enough speed to match up to that of the wave. A "gun" surfboard is the use more of the mechanical energy of the wave, in combination with their own paddling same width, but longer and thicker than a normal surfboard (called a "shortboard"); Keeping your balance while standing an is tricky because the forces acting on the board need to be balanced. Fig.2: Twiggy Baker on a critical moment during the take-off. Image: http://stabmag.com/news/heres-why-twiggy-baker-was-banned-from-the- mavericks-event/ Assume that the 19,2 m wave kept on moving at a constant speed of 45 km.h when Aaron was riding it. What was Aaron's speed, relative to the wave, at the top of the wave as he started the "take-off"'? 2.1 (1) What was Aaron's speed, relative to the earth, at the top of the wave as he started the "take-off"'? 2.2 (1) (2) 2.3 What is "mechanical energy"? What was Aaron's mechanical energy at the top of the wave? (Aaron and his board are a single system) 2.4 (4) Calculate Aaron's speed (in km · h-'), relative to the earth, at the bottom of the wave if all effects of friction are ignored. 2.5 All Rights Reserved: O Master Maths (Pty) Ltd S.NO TASK on his board moving along le in surfing, and cannot be ignor" : ALTERNATIVE ASSESSMI Schoolwer IEB ALTERNATIVE ASSESSMENT SBA MASTER SCIENCE TASK SVA03 Surfboard design The following pictures of surfboards show the shapes of 3 types of surfboards compared to each other by design (e.g. length, width, surface area, volume, mass, etc.). Allinear su mi o 0 200 *** A) Shortboard (3 kg) Surf Scienco B) "Gun" (7 kg) C) Longboard (12 kg) Images from: http://www.surfscience.com/ All 3 of the surfboards above are made from the same materials and their masses are representative of their volumes. A longboard is the thickest followed by a "gun" and then a shortboard. Which of surfboards A, B or C will 3.1.1 have the most manoeuvrability? 3.1.2 have the most inertia when moving on a wave? 3.1.3 be the best for a beginner (struggling with balance) to learn to surf with? 3.1.4 need the smallest force to paddle from rest? 3.1.5 exert the greatest lift (upwards force) on a surfer? 3.1 (5) All Rights Reserved: Master Maths (Pty) Lid MASTER SCIENCE TASK ALTERNATIVE ASSESSMENT D dams plays a very important role in surfing, and cannot be ignored. lowing diagram represents a surfer on his board moving along a wave. 2.6.1 normal force 2.6.2 frictional force 2.6.3 weight beeswax. Which letter (A -D) in the diagram represents the direction of the: (3) (4) 27 Surfers increase the friction on one surface of their boards by rubbing it with 2.7.1 Should the friction between the water and the board be high or low? Explain your answer by referring to the appropriate Newton's Law. 2.7.2 Should the friction between the surfer's feet and the board be high or low? Give a reason for your answer. 2.7.3 Refer to your answers in Q 2.7.1 and Q 2.7.2 to deduce whether surfers wax the top surface or the bottom surface of their surfboards. (5) (2) All Rights Reserved: O Mas SBA SVA03 mi ALTERNATIVE ASSESSMENT MASTER SCIENCE TASK (4) 2 It takes a lot of skill for a surfer to balance all the forces acting on a surfboard while riding a wave A very important skill in surfing smaller to medium waves is the ability to slow down or to speed up when riding the wave. Which surfboard design (A Bor C) will test allow a surfer to quickly change velocity when riding a wave? Explain your choice by naming and applying the relevant Newton's Law(s) of motion (4) 33 Give no reasons why a "pun" is used in big wave surfing, rather than a longboard, and motivate each reason with an explanation using appropriate Mechanics terminology 1601
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