A spring is taken from a drawer in a physics laboratory. (a) Fig. 8.1 is the extension-load graph for the spring. [Figure 8.1]

1. (a)(i)Using Fig. 8.1, determine the load on the spring when its extension is 4.9 cm. load = ..............................................................[1][1]
2. (a)(ii)The point X on Fig. 8.1 is the limit of proportionality for the spring. On Fig. 8.1, sketch a line to show how the extension-load graph might continue after X. [2][2]
3. (b)A rectangular, plastic block is suspended from the lower end of the spring. Fig. 8.2 shows that the bottom 3.5 cm of the plastic block is in the water in a beaker. [Figure 8.2] The density of water is 1000kg/m³ and the gravitational field strength g is 10N/kg. The base of the plastic block is a square with sides of 4.0 cm.
4. (b)(i)Calculate the pressure due to the water at a depth of 3.5cm below the surface of the water. pressure = ..............................................................[3][3]
5. (b)(ii)Calculate the upward force on the base of the block due to the pressure of the water. force = ....................................................................[2][2]
6. (b)(iii)In Fig. 8.2, the extension of the spring is 4.9 cm. Using the answer from (a)(i) and the answer from (b)(ii), determine the weight of the block. weight = ....................................................................[1][1]
7. (c)In the equipment shown in Fig. 8.2, the pressure of the atmosphere is transmitted through the water. The total pressure in the water at a depth of 3.5cm is larger than the pressure due to the water alone.
8. (c)(i)Explain why, in this experiment, atmospheric pressure does not affect the position of the plastic block in the water. ............................................................................................................................................... ...............................................................................................................................................[2][2]
9. (c)(ii)Force is a vector quantity and pressure is a scalar quantity. State how a vector quantity differs from a scalar quantity. ...............................................................................................................................................[1][1]
10. (d)The beaker in Fig. 8.2 is gradually moved upwards so that more of the plastic block is in the water. Explain what happens to the forces that act on the block. ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ...............................................................................................................................................[3][3]

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