9231 P21 - Nov 2019 - Q1 - 5 marks
A particle \(P\) is moving in a circle of radius 2 m . At time \(t\) seconds, its velocity is \((t-1)^{2} \mathrm{~m} \mathrm{~s}^{-1}\). At a particular time \(T\) seconds, where \(T>0\), the magnitude of the radial component of the acceleration of \(P\) is \(8 \mathrm{~m} \mathrm{~s}^{-2}\). Find the magnitude of the transverse component of the acceleration of \(P\) at this instant.
9231 P21 - Jun 2019 - Q1 - 4 marks
A particle \(P\) moves along an arc of a circle with centre \(O\) and radius 2 m . At time \(t\) seconds, the angle POA is \(\theta\), where \(\theta=1-\cos 2 t\), and \(A\) is a fixed point on the arc of the circle.
(i) Show that the magnitude of the radial component of the acceleration of \(P\) when \(t=\frac{1}{6} \pi\) is \(6 \mathrm{~m} \mathrm{~s}^{-2}\).
(ii) Find the magnitude of the transverse component of the acceleration of \(P\) when \(t=\frac{1}{6} \pi\).
9231 P21 - Nov 2017 - Q1 - 4 marks
A particle \(P\) is moving in a circle of radius 0.8 m . At time \(t \mathrm{~s}\) its velocity is \(\left(8-p t+t^{2}\right) \mathrm{m} \mathrm{s}^{-1}\), where \(p\) is a constant. The magnitude of the transverse component of the acceleration of \(P\) when \(t=2\) is zero. Find the magnitude of the radial component of the acceleration of \(P\) when \(t=2\).
9231 P23 - Jun 2018 - Q1 - 3 marks
A particle \(P\) is moving in a fixed circle of radius 0.8 m . At time \(t\) s its velocity is \(\left(t^{2}-t+2\right) \mathrm{m} \mathrm{s}^{-1}\). Find the magnitudes of the radial and the transverse components of the acceleration of \(P\) when \(t=2\).
9231 P31 - Nov 2025 - Q2 - 4 marks
A particle \(P\) of mass \(m\) is moving in a horizontal circle with angular speed \(\omega_{1}\) on the smooth inner surface of a hemispherical shell of radius \(r\). The angle between the upward vertical and the normal reaction of the surface on \(P\) is \(\theta_{1}\), where \(\tan \theta_{1}=\frac{3}{4}\).
When the angular speed is increased to \(\omega_{2}\), the angle between the upward vertical and the normal reaction of the surface on \(P\) becomes \(\theta_{2}\), where \(\tan \theta_{2}=\frac{4}{3}\). Find the ratio \(\frac{\omega_{1}}{\omega_{2}}\).
9231 P32 - Nov 2025 - Q1 - 4 marks
A particle \(P\) of mass \(m\) is attached to two light inextensible strings each of length \(l\). The end of one string is attached to a fixed point \(A\) and the end of the other string is attached to a fixed point \(B\), with \(A\) vertically above \(B\). Angle \(A P B\) is a right angle. The particle \(P\) rotates in a horizontal circle at a constant angular speed \(\omega\) with both strings taut (see diagram).
Find the tension in string \(A P\) in terms of \(m, g, l\) and \(\omega\).
9231 P34 - Nov 2025 - Q1 - 5 marks
A light inextensible string of length \(12 a\) is threaded through a fixed smooth ring \(R\). One end of the string is attached to a particle \(A\) of mass \(m\). The other end of the string is attached to a particle \(B\) of mass 0.5 m . Particle \(A\) hangs in equilibrium vertically below the ring. Particle \(B\) moves with constant angular speed \(\omega\) in a horizontal circle with particle \(A\) at its centre. The angle between \(A R\) and \(B R\) is \(\theta\) (see diagram).
Express \(\omega\) in terms of \(g\) and \(a\).
9231 P31 - Jun 2025 - Q3 - 7 marks
A rough horizontal disc rotates with constant angular speed \(\omega\,\text{rad s}^{-1}\). A particle \(P\) of mass \(1.6\) kg is at distance \(1.5\) m from the centre \(O\), attached to a point \(A\) vertically above \(O\) by a light elastic string. The natural length is \(2\) m, the modulus of elasticity is \(32\) N, and the coefficient of friction is \(0.5\). The particle is on the point of slipping in the direction \(OP\).
(a) Given that the tension is \(8\) N, show that \(\sin\alpha=0.6\).
(b) Find the number of revolutions per minute made by the disc and the particle.
9231 P33 - Jun 2025 - Q1 - 3 marks
A particle \(P\) of mass \(m\) is attached to one end of a light inextensible string of length \(a\). The other end is attached to a fixed point \(O\). The particle moves in a horizontal circle with constant angular speed \(\omega\), and the string is inclined at angle \(\theta\) to the downward vertical. Given \(\tan\theta=\frac43\), find \(\omega\) in terms of \(a\) and \(g\).
9231 P34 - Jun 2025 - Q4 - 6 marks
A hollow cone with a smooth inner surface is fixed with its vertex \(O\) downwards. The semi-vertical angle of the cone is \(\alpha\), where \(\tan\alpha=\dfrac34\). A light inextensible string has a particle \(A\) of mass \(m\) attached to one end and a particle \(B\) of mass \(m\) attached to the other end. The string passes through a small hole in the cone at \(O\).
Particle \(B\) hangs in equilibrium below \(O\). Particle \(A\) is on the inner surface of the cone at a height \(h\) above the level of \(O\) and moves in horizontal circles with constant angular speed \(\omega\).
Find \(\omega\) in terms of \(g\) and \(h\).
9231 P31 - Nov 2024 - Q6 - 8 marks
A particle \(P\) of mass \(0.05\,\text{kg}\) is attached to one end of a light inextensible string of length \(1\) m. The other end is attached to a fixed point \(O\). A particle \(Q\) of mass \(0.04\,\text{kg}\) is attached to one end of a second light inextensible string, whose other end is attached to \(P\).
The particle \(P\) moves in a horizontal circle of radius \(0.8\) m with angular speed \(\omega\,\text{rad s}^{-1}\). The particle \(Q\) moves in a horizontal circle of radius \(1.4\) m with the same angular speed. The centres of the circles are vertically below \(O\), and \(O\), \(P\), and \(Q\) are always in the same vertical plane. The strings \(OP\) and \(PQ\) make constant angles \(\alpha\) and \(\beta\) respectively with the vertical.
(a) Find the tension in the string \(OP\).
(b) Find \(\omega\).
(c) Find \(\beta\).
9231 P32 - Nov 2024 - Q1 - 3 marks
A particle of mass \(2\,\text{kg}\) is attached to one end of a light elastic string of natural length \(0.8\) m and modulus of elasticity \(100\) N. The other end is attached to a fixed point \(O\) on a smooth horizontal surface.
The particle moves in a horizontal circle about \(O\), with the string taut and with constant angular speed \(5\,\text{rad s}^{-1}\). Find the extension of the string.
9231 P31 - Jun 2024 - Q5 - 7 marks
Two particles \(A\) and \(B\), of masses \(m\) and \(km\) respectively, are connected by a light inextensible string of length \(a\). The particles are placed on a rough horizontal circular turntable with the string taut and lying along a radius of the turntable.
Particle \(A\) is at a distance \(a\) from the centre of the turntable, and particle \(B\) is at a distance \(2a\) from the centre. The coefficient of friction between each particle and the turntable is \(\dfrac15\).
When the turntable rotates with angular speed \(\dfrac25\sqrt{\dfrac ga}\), the system is in limiting equilibrium.
(a) Find the tension in the string, in terms of \(m\) and \(g\).
(b) Find \(k\).
9231 P33 - Jun 2024 - Q2 - 6 marks
A particle \(P\) of mass \(m\) is attached to one end of a light elastic string of natural length \(a\) and modulus of elasticity \(2mg\). A particle \(Q\) of mass \(km\) is attached to the other end.
Particle \(P\) lies on a smooth horizontal table. The string has part of its length in contact with the table and then passes through a small smooth hole \(H\) in the table.
Particle \(P\) moves in a horizontal circle on the surface of the table with constant speed \(\sqrt{\dfrac12ga}\). Particle \(Q\) hangs in equilibrium vertically below the hole with \(HQ=\dfrac14a\).
(a) Find, in terms of \(a\), the extension in the string.
(b) Find \(k\).
9231 P32 - Nov 2023 - Q1 - 4 marks
One end of a light inextensible string of length \(a\) is attached to a fixed point \(O\). The other end of the string is attached to a particle of mass \(m\). The string is taut and makes an angle \(\theta\) with the downward vertical through \(O\), where \(\cos\theta=\dfrac23\). The particle moves in a horizontal circle with speed \(v\).
Find \(v\) in terms of \(a\) and \(g\).
9231 P31 - Jun 2023 - Q5 - 7 marks
A light elastic string of natural length \(a\) and modulus of elasticity \(\lambda m g\) has one end attached to a fixed point \(O\) on a smooth horizontal surface. When a particle of mass \(m\) is attached to the free end of the string, it moves with speed \(v\) in a horizontal circle with centre \(O\) and radius \(x\). When, instead, a particle of mass \(2 m\) is attached to the free end of the string, this particle moves with speed \(\frac{1}{2} v\) in a horizontal circle with centre \(O\) and radius \(\frac{3}{4} x\).
(a) Find \(x\) in terms of \(a\).
(b) Given that \(v=\sqrt{12 a g}\), find the value of \(\lambda\).
9231 P33 - Jun 2023 - Q5 - 8 marks
One end of a light elastic string, of natural length \(12 a\) and modulus of elasticity \(k m g\), is attached to a fixed point \(O\). The other end of the string is attached to a particle of mass \(m\). The particle moves with constant speed \(\frac{3}{2} \sqrt{3 a g}\) in a horizontal circle with centre at a distance \(12 a\) below \(O\). The string is inclined at an angle \(\theta\) to the downward vertical through \(O\).
(a) Find, in terms of \(a\), the extension of the string.
(b) Find the value of \(k\).
9231 P31 - Nov 2022 - Q1 - 3 marks
A particle of mass 2 kg is attached to one end of a light inextensible string of length 0.6 m . The other end of the string is attached to a fixed point on a smooth horizontal surface. The particle is moving in a circular path on the surface. The tension in the string is 20 N .
Find how many revolutions the particle makes per minute.
9231 P31 - Jun 2021 - Q2 - 6 marks
A hollow hemispherical bowl of radius \(a\) has a smooth inner surface and is fixed with its axis vertical. A particle \(P\) of mass \(m\) moves in horizontal circles on the inner surface of the bowl, at a height \(x\) above the lowest point of the bowl. The speed of \(P\) is \(\sqrt{\frac{8}{3} g a}\).
Find \(x\) in terms of \(a\).
9231 P33 - Jun 2021 - Q3 - 6 marks
Particles \(A\) and \(B\), of masses \(3 m\) and \(m\) respectively, are connected by a light inextensible string of length \(a\) that passes through a fixed smooth ring \(R\). Particle \(B\) hangs in equilibrium vertically below the ring. Particle \(A\) moves in horizontal circles on a smooth horizontal surface with speed \(\frac{2}{5} \sqrt{g a}\). The angle between \(A R\) and \(B R\) is \(\theta\) (see diagram). The normal reaction between \(A\) and the surface is \(\frac{12}{5} m g\).
(a) Find \(\cos \theta\).
(b) Find, in terms of \(a\), the distance of \(B\) below the ring.
9231 P31 - Nov 2021 - Q1 - 4 marks
One end of a light elastic string, of natural length \(a\) and modulus of elasticity \(3 m g\), is attached to a fixed point \(O\) on a smooth horizontal plane. A particle \(P\) of mass \(m\) is attached to the other end of the string and moves in a horizontal circle with centre \(O\). The speed of \(P\) is \(\sqrt{\frac{4}{3} g a}\).
Find the extension of the string.
9231 P32 - Nov 2021 - Q3 - 6 marks
Particles \(A\) and \(B\), of masses \(m\) and \(3 m\) respectively, are connected by a light inextensible string of length \(a\) that passes through a fixed smooth ring \(R\). Particle \(B\) hangs in equilibrium vertically below the ring. Particle \(A\) moves in horizontal circles with speed \(v\). Particles \(A\) and \(B\) are at the same horizontal level. The angle between \(A R\) and \(B R\) is \(\theta\) (see diagram).
(a) Show that \(\cos \theta=\frac{1}{3}\).
(b) Find an expression for \(v\) in terms of \(a\) and \(g\).
9231 P31 - Jun 2020 - Q2 - 5 marks
A light inextensible string of length \(a\) is threaded through a fixed smooth ring \(R\). One end of the string is attached to a particle \(A\) of mass \(3 m\). The other end of the string is attached to a particle \(B\) of mass \(m\). The particle \(A\) hangs in equilibrium at a distance \(x\) vertically below the ring. The angle between \(A R\) and \(B R\) is \(\theta\) (see diagram). The particle \(B\) moves in a horizontal circle with constant angular speed \(2 \sqrt{\frac{g}{a}}\).
Show that \(\cos \theta=\frac{1}{3}\) and find \(x\) in terms of \(a\).
9231 P33 - Jun 2020 - Q1 - 2 marks
A particle \(P\) of mass \(m\) is attached to one end of a light inextensible string of length \(a\). The other end of the string is attached to a fixed point \(O\) on a smooth horizontal plane. The particle \(P\) moves in horizontal circles about \(O\). The tension in the string is \(4 m g\).
Find, in terms of \(a\) and \(g\), the time that \(P\) takes to make one complete revolution.
9231 P31 - Nov 2020 - Q3 - 6 marks
One end of a light elastic string, of natural length \(a\) and modulus of elasticity \(4 m g\), is attached to a fixed point \(O\). The other end of the string is attached to a particle of mass \(m\). The particle moves in a horizontal circle with a constant angular speed \(\sqrt{\frac{g}{a}}\) with the string inclined at an angle \(\theta\) to the downward vertical through \(O\). The length of the string during this motion is \((k+1) a\).
(a) Find the value of \(k\).
(b) Find the value of \(\cos \theta\).
9231 P32 - Nov 2020 - Q4 - 7 marks
A particle \(P\) of mass \(m\) is moving in a horizontal circle with angular speed \(\omega\) on the smooth inner surface of a hemispherical shell of radius \(r\). The angle between the vertical and the normal reaction of the surface on \(P\) is \(\theta\).
(a) Show that \(\cos \theta=\frac{g}{\omega^{2} r}\).
The plane of the circular motion is at a height \(x\) above the lowest point of the shell. When the angular speed is doubled, the plane of the motion is at a height \(4 x\) above the lowest point of the shell.
(b) Find \(x\) in terms of \(r\).