No questions found
The variation with time t of the displacement s for a car is shown in Fig. 1.1.
(a) Determine the magnitude of the average velocity between the times 5.0 s and 35.0 s. [2]
(b) On Fig. 1.2, sketch the variation with time t of the velocity v for the car. [4]
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(a) Define
(i) force, [1]
(ii) work done. [1]
(b) A force $F$ acts on a mass $m$ along a straight line for a distance $s$. The acceleration of the mass is $a$ and the speed changes from an initial speed $u$ to a final speed $v$.
(i) State the work $W$ done by $F$. [1]
(ii) Use your answer in (i) and an equation of motion to show that kinetic energy of a mass can be given by the expression
\( \text{kinetic energy} = \frac{1}{2} \times \text{mass} \times (\text{speed})^2. \) [3]
(c) A resultant force of $3800 \text{ N}$ causes a car of mass of $1500 \text{ kg}$ to accelerate from an initial speed of $15 \text{ ms}^{-1}$ to a final speed of $30 \text{ ms}^{-1}$.
(i) Calculate the distance moved by the car during this acceleration. [2]'
(ii) The same force is used to change the speed of the car from $30 \text{ ms}^{-1}$ to $45 \text{ ms}^{-1}$. Explain why the distance moved is not the same as that calculated in (i). [1]
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(a) Define
(i) stress, [1]
(ii) strain. [1]
(b) Explain the term $\textit{elastic limit}$. [1]
(c) Explain the term $\textit{ultimate tensile stress}$. [2]
(d) (i) A ductile material in the form of a wire is stretched up to its breaking point. On Fig. 3.1, sketch the variation with extension $x$ of the stretching force $F$. [2]
(ii) On Fig. 3.2, sketch the variation with $x$ of $F$ for a brittle material up to its breaking point. [1]
(e) (i) Explain the features of the graphs in (d) that show the characteristics of ductile and brittle materials. [2]
(ii) The force $F$ is removed from the materials in (d) just before the breaking point is reached. Describe the subsequent change in the extension for
- the ductile material, [1]
- the brittle material. [1]
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(a) Define electric field strength.
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[1]
(b) Two horizontal metal plates are 20 mm apart in a vacuum. A potential difference of 1.5 kV is applied across the plates, as shown in Fig. 4.1.
A charged oil drop of mass $5.0 \times 10^{-15}$ kg is held stationary by the electric field.
(i) On Fig. 4.1, draw lines to represent the electric field between the plates. [2]
(ii) Calculate the electric field strength between the plates.
electric field strength = .............................................. Vm$^{-1}$ [1]
(iii) Calculate the charge on the drop.
charge = .............................................. C [4]
(iv) The potential of the upper plate is increased. Describe and explain the subsequent motion of the drop.
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A potentiometer circuit that is used as a means of comparing potential differences is shown in Fig. 5.1.
A cell of e.m.f. $E_1$ and internal resistance $r_1$ is connected in series with a resistor of resistance $R_1$ and a uniform metal wire of total resistance $R_2$. A second cell of e.m.f. $E_2$ and internal resistance $r_2$ is connected in series with a sensitive ammeter and is then connected across the wire at BJ. The connection at J is halfway along the wire. The current directions are shown on Fig. 5.1.
(a) Use Kirchhoff’s laws to obtain the relation
(i) between the currents $I_1$, $I_2$ and $I_3$,
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(ii) between $E_1$, $R_1$, $R_2$, $r_1$, $I_1$ and $I_2$ in loop HBJFGH,
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(iii) between $E_1$, $E_2$, $r_1$, $r_2$, $R_1$, $R_2$, $I_1$ and $I_3$ in the loop HBCDJFGH.
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(b) The connection at J is moved along the wire. Explain why the reading on the ammeter changes.
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(a) State the principle of superposition. [2]
(b) An arrangement that can be used to determine the speed of sound in air is shown in Fig. 6.1.
Sound waves of constant frequency are emitted from the loudspeaker L and are reflected from a point S on a hard surface.
The loudspeaker is moved away from S until a stationary wave is produced.
Explain how sound waves from L give rise to a stationary wave between L and S. [2]
(c) A microphone connected to a cathode ray oscilloscope (c.r.o.) is positioned between L and S as shown in Fig. 6.1. The trace obtained on the c.r.o. is shown in Fig. 6.2.
The time-base setting on the c.r.o. is 0.10 ms cm-1.
(i) Calculate the frequency of the sound wave. [2]
(ii) The microphone is now moved towards S along the line LS. When the microphone is moved 6.7 cm, the trace seen on the c.r.o. varies from a maximum amplitude to a minimum and then back to a maximum.
- Use the properties of stationary waves to explain these changes in amplitude. [1]
- Calculate the speed of sound. [3]
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(a) State the experimental observations that show radioactive decay is
(i) spontaneous,
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(ii) random.
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(b) On Fig. 7.1, complete the charge and mass of $\alpha$-particles, $\beta$-particles and $\gamma$-radiation. Give example speeds of $\alpha$-particles and $\gamma$-radiation emitted by a laboratory source.
[Table_1: Fig. 7.1]
$$\begin{array}{|c|c|c|}\hline & \alpha\text{-particle} & \beta\text{-particle} & \gamma\text{-radiation} \\ \hline \text{charge} & & & 0 \\ \hline \text{mass} & 4u & & \\ \hline \text{speed} & & \text{up to } 0.99c & \\ \hline \end{array}$$
[3]
(c) Explain the process by which $\alpha$-particles lose energy when they pass through air.
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