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(a) Use the definition of work done to show that the SI base units of energy are kg m2 s-2.
[2]
(b) Define potential difference.
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[1]
(c) Determine the SI base units of resistance. Show your working.
units ............................................................... [3]
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A stone is thrown vertically upwards. The variation with time $t$ of the displacement $s$ of the stone is shown in Fig. 2.1.
(a) Use Fig. 2.1 to describe, without calculation, the speed of the stone from $t = 0$ to $t = 3.0s$. [2]
(b) Assume air resistance is negligible and therefore the stone has constant acceleration.
Calculate, for the stone,
(i) the speed at 3.0 s, [3]
(ii) the distance travelled from $t = 0$ to $t = 3.0, ext{s}$, [3]
(iii) the displacement from $t = 0$ to $t = 3.0, ext{s}$. [2]
(c) On Fig. 2.2, draw the variation with time $t$ of the velocity $v$ of the stone from $t = 0$ to $t = 3.0, ext{s}$. [3]
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A rod PQ is attached at P to a vertical wall, as shown in figure 1.
The length of the rod is 1.60 m. The weight $W$ of the rod acts 0.64 m from P. The rod is kept horizontal and in equilibrium by a wire attached to Q and to the wall at R. The wire provides a force $F$ on the rod of 44 N at 30° to the horizontal.
(a) Determine
(i) the vertical component of $F$, [1]
(ii) the horizontal component of $F$. [1]
(b) By taking moments about P, determine the weight $W$ of the rod. [2]
(c) Explain why the wall must exert a force on the rod at P. [1]
(d) On Figure 1, draw an arrow to represent the force acting on the rod at P. Label your arrow with the letter S. [1]
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(a) A gas molecule has a mass of $6.64 \times 10^{-27} \text{ kg}$ and a speed of $1250 \text{ ms}^{-1}$. The molecule collides normally with a flat surface and rebounds with the same speed, as shown in Fig. 4.1.
Calculate the change in momentum of the molecule. [2]
(b) (i) Use the kinetic model to explain the pressure exerted by gases. [3]
(ii) Explain the effect of an increase in density, at constant temperature, on the pressure of a gas. [1]
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599
(a) On Fig. 5.1, sketch the temperature characteristic of a thermistor.
[Image: Fig. 5.1 graph with resistance vs. temperature/°C]
(b) A potential divider circuit is shown in Fig. 5.2.
[Image: Fig. 5.2 circuit diagram]
The battery of electromotive force (e.m.f.) 12 V and negligible internal resistance is connected in series with resistors X and Y and thermistor Z. The resistance of Y is 15 kΩ and the resistance of Z at a particular temperature is 3.0 kΩ. The potential difference (p.d.) across Y is 8.0 V.
(i) Explain why the power transformed in the battery equals the total power transformed in X, Y, and Z.
...
[1]
(ii) Calculate the current in the circuit.
current = ... A
[2]
(iii) Calculate the resistance of X.
resistance = ... Ω
[3]
(iv) The temperature of Z is increased. State and explain the effect on the potential difference across Z.
...
[2]
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(a) State two differences between progressive waves and stationary waves.
(b) A source S of microwaves is placed in front of a metal reflector R, as shown in Fig. 6.1.
A microwave detector D is placed between R and S.
Describe
(i) how stationary waves are formed between R and S, [3]
(ii) how D is used to show that stationary waves are formed between R and S, [2]
(iii) how the wavelength of the microwaves may be determined using the apparatus in Fig. 6.1. [2]
(c) The wavelength of the microwaves in (b) is 2.8 cm. Calculate the frequency, in GHz, of the microwaves. [3]
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A uranium-235 nucleus absorbs a neutron and then splits into two nuclei. A possible nuclear reaction is given by
$$^{235}_{92}U + ^{a}_{b}n \rightarrow ^{93}_{37}Rb + ^{c}_{d}X + 2^{a}_{b}n + \text{ energy.}$$
(a) State the constituent particles of the uranium-235 nucleus.
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(b) Complete Fig. 7.1 for this reaction.
[3]
(c) Suggest a possible form of energy released in this reaction.
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(d) Explain, using the law of mass-energy conservation, how energy is released in this reaction.
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