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(a) (i) Define acceleration. [1]
(ii) State Newton's first law of motion. [1]
(b) The variation with time $t$ of vertical speed $v$ of a parachutist falling from an aircraft is shown in Fig. 1.1.
(i) Calculate the distance travelled by the parachutist in the first 3.0 s of the motion. [2]
(ii) Explain the variation of the resultant force acting on the parachutist from $t = 0$ (point A) to $t = 15s$ (point C). [3]
(iii) Describe the changes to the frictional force on the parachutist
1. at $t = 15s$ (point C), [1]
2. between $t = 15s$ (point C) and $t = 22s$ (point E). [1]
(iv) The mass of the parachutist is 95 kg.
Calculate, for the parachutist between $t = 15s$ (point C) and $t = 17s$ (point D),
1. the average acceleration, [2]
2. the average frictional force. [3]
501
556
551
(a) Define electrical \textit{resistance}. [1]
(b) A circuit is set up to measure the resistance $R$ of a metal wire. The potential difference (p.d.) $V$ across the wire and the current $I$ in the wire are to be measured.
(i) Draw a circuit diagram of the apparatus that could be used to make these measurements. [3]
(ii) Readings for p.d. $V$ and the corresponding current $I$ are obtained. These are shown in Fig. 2.1.
Explain how Fig. 2.1 indicates that the readings are subject to
1. a systematic uncertainty, [1]
2. random uncertainties. [1]
(iii) Use data from Fig. 2.1 to determine $R$. Explain your working. [3]
(c) In another experiment, a value of $R$ is determined from the following data:
Current $I = 0.64 \pm 0.01 \text{ A}$ and p.d. $V = 6.8 \pm 0.1 \text{ V}$.
Calculate the value of $R$, together with its uncertainty. Give your answer to an appropriate number of significant figures. [3]
558
503
555
(a) Define pressure. [1]
(b) Explain, in terms of the air molecules, why the pressure at the top of a mountain is less than at sea level. [3]
(c) Figure shows a liquid in a cylindrical container.
The cross-sectional area of the container is $0.450 \text{ m}^2$. The height of the column of liquid is $0.250 \text{ m}$ and the density of the liquid is $13600 \text{ kg/m}^3$.
(i) Calculate the weight of the column of liquid. [3]
(ii) Calculate the pressure on the base of the container caused by the weight of the liquid. [1]
(iii) Explain why the pressure exerted on the base of the container is different from the value calculated in (ii). [1]
521
551
565
(a) Describe the diffraction of monochromatic light as it passes through a diffraction grating. [2]
(b) White light is incident on a diffraction grating, as shown in Fig. 4.1.
The diffraction pattern formed on the screen has white light, called zero order, and coloured spectra in other orders.
(i) Describe how the principle of superposition is used to explain
- white light at the zero order, [2]
- the difference in position of red and blue light in the first-order spectrum. [2]
(ii) Light of wavelength 625 nm produces a second-order maximum at an angle of 61.0° to the incident direction. Determine the number of lines per metre of the diffraction grating. [2]
(iii) Calculate the wavelength of another part of the visible spectrum that gives a maximum for a different order at the same angle as in (ii). [2]
506
600
539
(a) Explain what is meant by plastic deformation. [1]
(b) A copper wire of uniform cross-sectional area $1.54 \times 10^{-6} \text{ m}^2$ and length $1.75 \text{ m}$ has a breaking stress of $2.20 \times 10^8 \text{ Pa}$. The Young modulus of copper is $1.20 \times 10^{11} \text{ Pa}$.
(i) Calculate the breaking force of the wire. [2]
(ii) A stress of $9.0 \times 10^7 \text{ Pa}$ is applied to the wire. Calculate the extension. [2]
(c) Explain why it is not appropriate to use the Young modulus to determine the extension when the breaking force is applied. [1]
567
575
551
(a) Describe the structure of an atom of the nuclide $^{235}_{92}\text{U}$.
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...........................................................................................................................[2]
(b) The deflection of $\alpha$-particles by a thin metal foil is investigated with the arrangement shown in Fig. 6.1. All the apparatus is enclosed in a vacuum.
The detector of $\alpha$-particles, D, is moved around the path labelled WXY.
(i) Explain why the apparatus is enclosed in a vacuum.
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...........................................................................................................................[1]
(ii) State and explain the readings detected by D when it is moved along WXY.
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...........................................................................................................................[3]
(c) A beam of $\alpha$-particles produces a current of 1.5pA. Calculate the number of $\alpha$-particles per second passing a point in the beam.
number = .................................................... s$^{-1}$ [3]
541
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508
