No questions found
(a) State the SI base units of force.
................................................................. [1]
(b) Two wires each of length \( l \) are placed parallel to each other a distance \( x \) apart, as shown in Fig. 1.1.
Each wire carries a current \( I \). The currents give rise to a force \( F \) on each wire given by
\[ F = \frac{KI^2l}{x} \] where \( K \) is a constant.
(i) Determine the SI base units of \( K \).
units of \( K \) ..................................................... [2]
(ii) On Fig. 1.2, sketch the variation with \( x \) of \( F \). The quantities \( I \) and \( l \) remain constant.
[2]
(iii) The current \( I \) in both of the wires is varied.
On Fig. 1.3, sketch the variation with \( I \) of \( F \). The quantities \( x \) and \( l \) remain constant.
[1]
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(a) A student walks from A to B along the path shown in Fig. 2.1.
The student takes time $t$ to walk from A to B.
(i) State the quantity, apart from $t$, that must be measured in order to determine the average value of
1. speed, [1]
2. velocity. [1]
(ii) Define $\textit{acceleration}$. [1]
(b) A girl falls vertically onto a trampoline, as shown in Fig. 2.2.
The trampoline consists of a central section supported by springy material. At time $t = 0$ the girl starts to fall. The girl hits the trampoline and rebounds vertically. The variation with time $t$ of velocity $v$ of the girl is illustrated in Fig. 2.3.
For the motion of the girl, calculate
(i) the distance fallen between time $t = 0$ and when she hits the trampoline, [2]
(ii) the average acceleration during the rebound. [2]
(c) (i) Use Fig. 2.3 to compare, without calculation, the accelerations of the girl before and after the rebound. Explain your answer. [2]
(ii) Use Fig. 2.3 to compare, without calculation, the potential energy of the girl at $t = 0$ and $t = 1.85$ s. Explain your answer. [2]
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(a) (i) State the principle of conservation of momentum.
(a) (ii) State the difference between an elastic and an inelastic collision.
(b) An object A of mass 4.2 kg and horizontal velocity $3.6 \text{ ms}^{-1}$ moves towards object B as shown in Fig. 3.1.
Object B of mass 1.5 kg is moving with a horizontal velocity of $1.2 \text{ ms}^{-1}$ towards object A.
The objects collide and then both move to the right, as shown in Fig. 3.2.
Object A has velocity $v$ and object B has velocity $3.0 \text{ ms}^{-1}$.
(i) Calculate the velocity $v$ of object A after the collision. [3]
(ii) Determine whether the collision is elastic or inelastic. [3]
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(a) Define
(i) stress, [1]
(ii) strain. [1]
(b) The Young modulus of the metal of a wire is 0.17 TPa. The cross-sectional area of the wire is 0.18 mm^2.
The wire is extended by a force $F$. This causes the length of the wire to be increased by 0.095%.
Calculate
(i) the stress, [4]
(ii) the force $F$. [2]
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(a) Explain the principle of superposition. [2]
(b) Sound waves travel from a source S to a point X along two paths SX and SPX, as shown in Fig. 5.1.
(i) State the phase difference between these waves at X for this to be the position of
1. a minimum,
phase difference = ....................................... unit ............................... [1]
2. a maximum.
phase difference = ....................................... unit ............................... [1]
(ii) The frequency of the sound from S is 400 Hz and the speed of sound is 320 m s^{-1}.
Calculate the wavelength of the sound waves. [2]
(iii) The distance SP is 3.0 m and the distance PX is 4.0 m. The angle SPX is 90°. Suggest whether a maximum or a minimum is detected at point X. Explain your answer. [2]
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(a) Define potential difference (p.d.).
..............................................................................................................................[1]
(b) A battery of electromotive force 20V and zero internal resistance is connected in series with two resistors $R_1$ and $R_2$, as shown in Fig. 6.1.
The resistance of $R_2$ is $600Ω$. The resistance of $R_1$ is varied from 0 to $400Ω$. Calculate
(i) the maximum p.d. across $R_2$,
maximum p.d. = .....................................V [1]
(ii) the minimum p.d. across $R_2$.
minimum p.d. = .....................................V [2]
(c) A light-dependent resistor (LDR) is connected in parallel with $R_2$, as shown in Fig. 6.2.
When the light intensity is varied, the resistance of the LDR changes from $5.0kΩ$ to $1.2kΩ$.
(i) For the maximum light intensity, calculate the total resistance of $R_2$ and the LDR.
total resistance = .....................................Ω [2]
(ii) The resistance of $R_1$ is varied from 0 to $400Ω$ in the circuits of Fig. 6.1 and Fig. 6.2. State and explain the difference, if any, between the minimum p.d. across $R_2$ in each circuit. Numerical values are not required.
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[2]
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(a) Two isotopes of uranium are uranium-235 $(^{235}_{92}\text{U})$ and uranium-238 $(^{238}_{92}\text{U})$.
(i) Describe in detail an atom of uranium-235.
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....................................................................................................................... [4]
(ii) With reference to the two forms of uranium, explain the term $\textit{isotopes}$.
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(b) When a uranium-235 nucleus absorbs a neutron, the following reaction may occur:
$$^{235}_{92}\text{U} + ^{W}_{X}\text{n} \rightarrow ^{148}_{57}\text{La} + ^{Z}_{Y}\text{Q} + 3^{W}_{X}\text{n}$$
(i) Determine the values of $Y$ and $Z$.
$Y = .....$
$Z = .....$ [2]
(ii) Explain why the sum of the masses of the uranium nucleus and of the neutron does not equal the total mass of the products of the reaction.
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....................................................................................................................... [2]
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